// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/trees/proxy_impl.h"

#include <string.h>

#include <algorithm>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/auto_reset.h"
#include "base/check.h"
#include "base/functional/bind.h"
#include "base/memory/raw_ptr.h"
#include "base/metrics/histogram_functions.h"
#include "base/notreached.h"
#include "base/task/common/task_annotator.h"
#include "base/task/single_thread_task_runner.h"
#include "base/trace_event/trace_event.h"
#include "base/trace_event/traced_value.h"
#include "base/trace_event/typed_macros.h"
#include "base/types/optional_ref.h"
#include "cc/base/devtools_instrumentation.h"
#include "cc/base/features.h"
#include "cc/benchmarks/benchmark_instrumentation.h"
#include "cc/input/browser_controls_offset_manager.h"
#include "cc/input/browser_controls_offset_tag_modifications.h"
#include "cc/metrics/compositor_timing_history.h"
#include "cc/paint/paint_image.h"
#include "cc/paint/paint_worklet_layer_painter.h"
#include "cc/scheduler/scheduler_state_machine.h"
#include "cc/trees/client_layer_tree_host_impl.h"
#include "cc/trees/commit_state.h"
#include "cc/trees/compositor_commit_data.h"
#include "cc/trees/layer_tree_frame_sink.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_impl.h"
#include "cc/trees/layer_tree_mutator.h"
#include "cc/trees/layer_tree_settings.h"
#include "cc/trees/mutator_host.h"
#include "cc/trees/proxy_main.h"
#include "cc/trees/render_frame_metadata_observer.h"
#include "cc/trees/swap_promise.h"
#include "cc/trees/task_runner_provider.h"
#include "cc/trees/trace_utils.h"
#include "components/viz/common/frame_sinks/begin_frame_args.h"
#include "components/viz/common/frame_sinks/delay_based_time_source.h"
#include "components/viz/common/frame_timing_details.h"
#include "components/viz/common/gpu/raster_context_provider.h"
#include "gpu/command_buffer/client/raster_interface.h"
#include "services/metrics/public/cpp/ukm_recorder.h"

namespace cc {

namespace {

// Measured in seconds.
constexpr auto kSmoothnessTakesPriorityExpirationDelay =
    base::Milliseconds(250);

// This is only used in view transitions. The risk of this timer firing early
// is that the view transition fails a capture, resulting in a blank "old"
// state. However, the risk of not having a timeout is that we erroneously
// prevent rendering until the window forces another hidden state (e.g. minimize
// or switch tabs). This signal should be sent at roughly the same time as we
// unpause rendering, since we wait until visibility change only if the document
// is hidden.
//
// TODO(vmpstr): We need to revisit this after we gather enough metrics of how
// often this triggers.
constexpr auto kPauseRenderingUntilVisibilityChangeTimeout =
    base::Milliseconds(300);

}  // namespace

// Ensures that a CompletionEvent for commit is always signaled.
class ScopedCommitCompletionEvent {
 public:
  ScopedCommitCompletionEvent(
      int source_frame_number,
      CompletionEvent* event,
      base::TimeTicks start_time,
      base::SingleThreadTaskRunner* main_thread_task_runner,
      bool notify_main,
      base::WeakPtr<ProxyMain> proxy_main_weak_ptr)
      : source_frame_number_(source_frame_number),
        event_(event),
        commit_timestamps_({start_time, base::TimeTicks()}),
        main_thread_task_runner_(main_thread_task_runner),
        notify_main_(notify_main),
        proxy_main_weak_ptr_(proxy_main_weak_ptr) {}
  ScopedCommitCompletionEvent(const ScopedCommitCompletionEvent&) = delete;
  ~ScopedCommitCompletionEvent() {
    event_.ExtractAsDangling()->Signal();
    if (notify_main_) {
      main_thread_task_runner_->PostTask(
          FROM_HERE,
          base::BindOnce(&ProxyMain::DidCompleteCommit, proxy_main_weak_ptr_,
                         source_frame_number_, commit_timestamps_));
    }
  }
  ScopedCommitCompletionEvent& operator=(const ScopedCommitCompletionEvent&) =
      delete;

  void SetFinishTime(base::TimeTicks finish_time) {
    commit_timestamps_.finish = finish_time;
  }

 private:
  const int source_frame_number_;
  raw_ptr<CompletionEvent> event_;
  CommitTimestamps commit_timestamps_;
  raw_ptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
  bool notify_main_;
  base::WeakPtr<ProxyMain> proxy_main_weak_ptr_;
};

ProxyImpl::ProxyImpl(base::WeakPtr<ProxyMain> proxy_main_weak_ptr,
                     LayerTreeHost* layer_tree_host,
                     int id,
                     const LayerTreeSettings* settings,
                     TaskRunnerProvider* task_runner_provider)
    : layer_tree_host_id_(id),
      next_frame_is_newly_committed_frame_(false),
      inside_draw_(false),
      task_runner_provider_(task_runner_provider),
      smoothness_priority_expiration_notifier_(
          task_runner_provider->ImplThreadTaskRunner(),
          base::BindRepeating(&ProxyImpl::RenewTreePriority,
                              base::Unretained(this)),
          kSmoothnessTakesPriorityExpirationDelay),
      proxy_main_weak_ptr_(proxy_main_weak_ptr) {
  TRACE_EVENT0("cc", "ProxyImpl::ProxyImpl");
  DCHECK(IsImplThread());
  DCHECK(IsMainThreadBlocked());

  host_impl_ = layer_tree_host->CreateLayerTreeHostImpl(this);

  SchedulerSettings scheduler_settings(settings->ToSchedulerSettings());
  scheduler_settings.main_frame_before_commit_enabled = true;

  std::unique_ptr<CompositorTimingHistory> compositor_timing_history(
      new CompositorTimingHistory(CompositorTimingHistory::RENDERER_UMA));
  scheduler_ = std::make_unique<Scheduler>(
      this, scheduler_settings, layer_tree_host_id_,
      task_runner_provider_->ImplThreadTaskRunner(),
      std::move(compositor_timing_history),
      host_impl_->compositor_frame_reporting_controller());

  DCHECK_EQ(scheduler_->visible(), host_impl_->visible());
}

ProxyImpl::~ProxyImpl() {
  TRACE_EVENT0("cc", "ProxyImpl::~ProxyImpl");
  DCHECK(IsImplThread());
  DCHECK(IsMainThreadBlocked());

  // Prevent the scheduler from performing scheduled actions while we're in an
  // inconsistent state.
  scheduler_->Stop();

  // Take away the LayerTreeFrameSink before destroying things so it doesn't
  // try to call into its client mid-shutdown.
  host_impl_->ReleaseLayerTreeFrameSink();

  // The `Scheduler` has a raw_ptr to the CompositorFrameReportingController
  // that is owned by the LTHI.
  scheduler_->TearDown();

  // It is important to destroy LTHI before the Scheduler since it can make
  // callbacks that access it during destruction cleanup.
  host_impl_ = nullptr;
  scheduler_ = nullptr;

  // We need to explicitly shutdown the notifier to destroy any weakptrs it is
  // holding while still on the compositor thread. This also ensures any
  // callbacks holding a ProxyImpl pointer are cancelled.
  smoothness_priority_expiration_notifier_.Shutdown();
}

void ProxyImpl::InitializeMutatorOnImpl(
    std::unique_ptr<LayerTreeMutator> mutator) {
  TRACE_EVENT0("cc", "ProxyImpl::InitializeMutatorOnImpl");
  DCHECK(IsImplThread());
  host_impl_->SetLayerTreeMutator(std::move(mutator));
}

void ProxyImpl::InitializePaintWorkletLayerPainterOnImpl(
    std::unique_ptr<PaintWorkletLayerPainter> painter) {
  TRACE_EVENT0("cc", "ProxyImpl::InitializePaintWorkletLayerPainterOnImpl");
  DCHECK(IsImplThread());
  host_impl_->SetPaintWorkletLayerPainter(std::move(painter));
}

void ProxyImpl::UpdateBrowserControlsStateOnImpl(
    BrowserControlsState constraints,
    BrowserControlsState current,
    bool animate,
    base::optional_ref<const BrowserControlsOffsetTagModifications>
        offset_tag_modifications) {
  DCHECK(IsImplThread());
  host_impl_->browser_controls_manager()->UpdateBrowserControlsState(
      constraints, current, animate, offset_tag_modifications);
}

void ProxyImpl::InitializeLayerTreeFrameSinkOnImpl(
    LayerTreeFrameSink* layer_tree_frame_sink,
    base::WeakPtr<ProxyMain> proxy_main_frame_sink_bound_weak_ptr) {
  TRACE_EVENT0("cc", "ProxyImpl::InitializeLayerTreeFrameSinkOnImplThread");
  DCHECK(IsImplThread());

  proxy_main_frame_sink_bound_weak_ptr_ = proxy_main_frame_sink_bound_weak_ptr;

  ClientLayerTreeHostImpl* host_impl = host_impl_.get();
  bool success = host_impl->InitializeFrameSink(layer_tree_frame_sink);
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::DidInitializeLayerTreeFrameSink,
                                proxy_main_weak_ptr_, success));
  if (success)
    scheduler_->DidCreateAndInitializeLayerTreeFrameSink();
}

bool ProxyImpl::ShouldDeferBeginMainFrame() const {
  return main_wants_defer_begin_main_frame_ ||
         impl_wants_defer_begin_main_frame_;
}

void ProxyImpl::SetDeferBeginMainFrameFromMain(bool defer_begin_main_frame) {
  // This is the impl-side update of a main-thread request (that is, through
  // ProxyMain::SetDeferMainFrameUpdate) to defer BeginMainFrame.
  DCHECK(IsImplThread());
  bool was_deferring = ShouldDeferBeginMainFrame();

  main_wants_defer_begin_main_frame_ = defer_begin_main_frame;

  bool should_defer = ShouldDeferBeginMainFrame();
  if (was_deferring != should_defer)
    scheduler_->SetDeferBeginMainFrame(ShouldDeferBeginMainFrame());
}

void ProxyImpl::SetPauseRendering(bool pause_rendering,
                                  bool delay_until_visibility_change) {
  CHECK(IsImplThread());
  if (!pause_rendering && delay_until_visibility_change &&
      host_impl_->visible()) {
    // TODO(crbug.com/537790296): This timeout is necessary to avoid situations
    // when the visibility change never happens. We need to investigate when
    // that is the case (see the histogram recorded).
    pause_rendering_until_visibility_change_timer_->Start(
        FROM_HERE, kPauseRenderingUntilVisibilityChangeTimeout, this,
        &ProxyImpl::OnPauseRenderingUntilVisibilityChangeTimeout);
  } else {
    pause_rendering_until_visibility_change_timer_->Stop();
    scheduler_->SetPauseRendering(pause_rendering);
  }
}

void ProxyImpl::OnPauseRenderingUntilVisibilityChangeTimeout() {
  TRACE_EVENT0("cc", "ProxyImpl::OnPauseRenderingUntilVisibilityChangeTimeout");
  CHECK(IsImplThread());
  base::UmaHistogramBoolean(
      "Compositing.Renderer.PauseRenderingUntilVisibilityChangeTimeout", true);
  scheduler_->SetPauseRendering(false);
}

void ProxyImpl::SetDeferBeginMainFrameFromImpl(bool defer_begin_main_frame) {
  // This is a request from the impl thread to defer BeginMainFrame.
  DCHECK(IsImplThread());
  bool was_deferring = ShouldDeferBeginMainFrame();

  impl_wants_defer_begin_main_frame_ = defer_begin_main_frame;

  bool should_defer = ShouldDeferBeginMainFrame();
  if (was_deferring != should_defer)
    scheduler_->SetDeferBeginMainFrame(ShouldDeferBeginMainFrame());
}

void ProxyImpl::SendEarlyFinalBeginMainFrame() {
  // Triggers a fake vsync
  scheduler_->SendEarlyFinalBeginMainFrame();
  host_impl_->DidSendEarlyFinalBeginMainFrame();
}

void ProxyImpl::SetNeedsRedrawOnImpl(const gfx::Rect& damage_rect) {
  DCHECK(IsImplThread());
  host_impl_->SetViewportDamage(damage_rect);
  SetNeedsRedrawOnImplThread();
}

void ProxyImpl::SetNeedsCommitOnImpl(BeginMainFrameReason reason,
                                     bool urgent,
                                     bool unthrottle) {
  SetNeedsCommitOnImplThread(reason, urgent, unthrottle);
}

void ProxyImpl::SetTargetLocalSurfaceIdOnImpl(
    const viz::LocalSurfaceId& target_local_surface_id) {
  DCHECK(IsImplThread());
  host_impl_->SetTargetLocalSurfaceId(target_local_surface_id);
}

void ProxyImpl::BeginMainFrameAbortedOnImpl(
    CommitEarlyOutReason reason,
    base::TimeTicks main_thread_start_time,
    std::vector<std::unique_ptr<SwapPromise>> swap_promises,
    bool scroll_and_viewport_changes_synced) {
  TRACE_EVENT1("cc", "ProxyImpl::BeginMainFrameAbortedOnImplThread", "reason",
               CommitEarlyOutReasonToString(reason));
  DCHECK(IsImplThread());
  DCHECK(scheduler_->CommitPending());

  host_impl_->BeginMainFrameAborted(
      reason, std::move(swap_promises),
      scheduler_->last_dispatched_begin_main_frame_args(),
      static_cast<bool>(data_for_commit_.get()),
      scroll_and_viewport_changes_synced);
  scheduler_->NotifyBeginMainFrameStarted(main_thread_start_time);
  scheduler_->BeginMainFrameAborted(reason);
}

void ProxyImpl::SetVisibleOnImpl(bool visible) {
  TRACE_EVENT1("cc", "ProxyImpl::SetVisibleOnImplThread", "visible", visible);
  DCHECK(IsImplThread());
  host_impl_->SetVisible(visible);
  scheduler_->SetVisible(visible);

  if (pause_rendering_until_visibility_change_timer_->IsRunning()) {
    pause_rendering_until_visibility_change_timer_->Stop();
    scheduler_->SetPauseRendering(false);
  }
}

void ProxyImpl::SetShouldWarmUpOnImpl() {
  TRACE_EVENT0("cc", "ProxyImpl::SetShouldWarmUpOnImpl");
  DCHECK(IsImplThread());
  scheduler_->SetShouldWarmUp();
}

void ProxyImpl::ReleaseLayerTreeFrameSinkOnImpl(CompletionEvent* completion) {
  TRACE_EVENT0("cc", "ProxyImpl::ReleaseLayerTreeFrameSinkOnImpl");
  base::ScopedUmaHistogramTimer histogram_timer(
      "Navigation.ProxyImpl.ReleaseLayerTreeFrameSinkOnImpl");
  DCHECK(IsImplThread());

  // Unlike DidLoseLayerTreeFrameSinkOnImplThread, we don't need to call
  // LayerTreeHost::DidLoseLayerTreeFrameSink since it already knows.
  scheduler_->DidLoseLayerTreeFrameSink();
  host_impl_->ReleaseLayerTreeFrameSink();
  completion->Signal();
}

void ProxyImpl::FinishGLOnImpl(CompletionEvent* completion) {
  TRACE_EVENT0("cc", "ProxyImpl::FinishGLOnImplThread");
  DCHECK(IsImplThread());
  if (host_impl_->layer_tree_frame_sink()) {
    auto* context_provider =
        host_impl_->layer_tree_frame_sink()->context_provider();
    if (context_provider) {
      context_provider->RasterInterface()->Finish();
    }
  }
  completion->Signal();
}

void ProxyImpl::MainFrameWillHappenOnImplForTesting(
    CompletionEvent* completion,
    bool* main_frame_will_happen) {
  DCHECK(IsImplThread());
  if (host_impl_->layer_tree_frame_sink()) {
    *main_frame_will_happen = scheduler_->MainFrameForTestingWillHappen();
  } else {
    *main_frame_will_happen = false;
  }
  completion->Signal();
}

bool ProxyImpl::IsInSynchronousComposite() const {
  return false;
}

void ProxyImpl::FrameSinksToThrottleUpdated(
    const base::flat_set<viz::FrameSinkId>& ids) {
  NOTREACHED();
}

void ProxyImpl::SetHasActiveThreadedScroll(bool is_scrolling) {
  scheduler_->SetIsScrolling(is_scrolling);
}

void ProxyImpl::SetWaitingForScrollEvent(bool waiting_for_scroll_event) {
  scheduler_->SetWaitingForScrollEvent(waiting_for_scroll_event);
}

void ProxyImpl::SetUnboundedFrameSink(
    std::unique_ptr<LayerTreeFrameSink> unbounded_frame_sink,
    const viz::LocalSurfaceId& local_surface_id) {
  DCHECK(IsImplThread());
  host_impl_->SetUnboundedFrameSink(std::move(unbounded_frame_sink),
                                    local_surface_id);
}

void ProxyImpl::SetUnboundedFrameSinkId(
    const viz::FrameSinkId& frame_sink_id,
    const viz::LocalSurfaceId& local_surface_id) {
  DCHECK(IsImplThread());
  CHECK(base::FeatureList::IsEnabled(features::kTreesInViz));
  host_impl_->SetUnboundedFrameSinkId(frame_sink_id, local_surface_id);
}

void ProxyImpl::DismissUnboundedFrameSink() {
  DCHECK(IsImplThread());
  host_impl_->DismissUnboundedFrameSink();
}

void ProxyImpl::SetUnboundedLocalSurfaceId(
    const viz::LocalSurfaceId& local_surface_id) {
  DCHECK(IsImplThread());
  host_impl_->SetUnboundedLocalSurfaceId(local_surface_id);
}

void ProxyImpl::NotifyReadyToCommitOnImpl(
    CompletionEvent* completion_event,
    std::unique_ptr<CommitState> commit_state,
    const ThreadUnsafeCommitState* unsafe_state,
    base::TimeTicks main_thread_start_time,
    bool scroll_and_viewport_changes_synced,
    CommitTimestamps* commit_timestamps,
    bool commit_timeout) {
  TRACE_EVENT("cc,benchmark", "ProxyImpl::ReadyToCommit",
              [&](perfetto::EventContext ctx) {
                EmitMainFramePipelineStep(
                    ctx, commit_state->trace_id,
                    perfetto::protos::pbzero::MainFramePipeline::Step::
                        READY_TO_COMMIT_ON_IMPL);
              });

  DCHECK(!data_for_commit_.get());
  DCHECK(IsImplThread());
  DCHECK(scheduler_);
  DCHECK(scheduler_->CommitPending());

  // Inform the layer tree host that the commit has started, so that metrics
  // can determine how long we waited for thread synchronization.
  //
  // If the main thread is blocked waiting for commit, then commit_timestamps
  // points to a variable on the call stack of the main thread. If the main
  // thread is not blocked, then the commit timestamps are transmitted back to
  // the main thread by ScopedCommitCompletionEvent.
  DCHECK_EQ((bool)commit_timestamps,
            task_runner_provider_->IsMainThreadBlocked());
  base::TimeTicks start_time = base::TimeTicks::Now();
  if (commit_timestamps)
    commit_timestamps->start = start_time;

  if (!host_impl_) {
    TRACE_EVENT_INSTANT("cc", "EarlyOut_NoLayerTree");
    completion_event->Signal();
    return;
  }

  // Ideally, we should inform to impl thread when BeginMainFrame is started.
  // But, we can avoid a PostTask in here.
  scheduler_->NotifyBeginMainFrameStarted(main_thread_start_time);

  auto& begin_main_frame_metrics = commit_state->begin_main_frame_metrics;
  host_impl_->ReadyToCommit(scroll_and_viewport_changes_synced,
                            begin_main_frame_metrics.get(), commit_timeout);

  int source_frame_number = commit_state->source_frame_number;
  data_for_commit_ = std::make_unique<DataForCommit>(
      std::make_unique<ScopedCommitCompletionEvent>(
          source_frame_number, completion_event, start_time,
          MainThreadTaskRunner(),
          /*notify_main*/ !commit_timestamps, proxy_main_weak_ptr_),
      std::move(commit_state), unsafe_state, commit_timestamps);

  // Extract metrics data from the layer tree host and send them to the
  // scheduler to pass them to the compositor_timing_history object.
  scheduler_->NotifyReadyToCommit(std::move(begin_main_frame_metrics));

  // If scroll offsets were not synchronized by this commit we need another main
  // frame to sync them.
  // Note that scroll_and_viewport_changes_synced will be false for the frame
  // that contains the first contentful paint, since paint holding makes us skip
  // ApplyCompositorChanges. This means we are guaranteed to run another main
  // frame after FCP, which is good because there may be hover effects to apply.
  if (!scroll_and_viewport_changes_synced)
    scheduler_->SetNeedsBeginMainFrame(false);
}

void ProxyImpl::DidLoseLayerTreeFrameSinkOnImplThread() {
  TRACE_EVENT0("cc", "ProxyImpl::DidLoseLayerTreeFrameSinkOnImplThread");
  DCHECK(IsImplThread());
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::DidLoseLayerTreeFrameSink,
                                proxy_main_weak_ptr_));
  scheduler_->DidLoseLayerTreeFrameSink();
}

void ProxyImpl::SetBeginFrameSource(viz::BeginFrameSource* source) {
  // During shutdown, destroying the LayerTreeFrameSink may unset the
  // viz::BeginFrameSource.
  if (scheduler_) {
    // TODO(enne): this overrides any preexisting begin frame source.  Those
    // other sources will eventually be removed and this will be the only path.
    scheduler_->SetBeginFrameSource(source);
  }
}

void ProxyImpl::DidReceiveCompositorFrameAckOnImplThread() {
  TRACE_EVENT0("cc,benchmark",
               "ProxyImpl::DidReceiveCompositorFrameAckOnImplThread");
  DCHECK(IsImplThread());
  scheduler_->DidReceiveCompositorFrameAck();
}

void ProxyImpl::OnCanDrawStateChanged(bool can_draw) {
  TRACE_EVENT1("cc", "ProxyImpl::OnCanDrawStateChanged", "can_draw", can_draw);
  DCHECK(IsImplThread());
  scheduler_->SetCanDraw(can_draw);
}

void ProxyImpl::NotifyReadyToActivate() {
  DCHECK(IsImplThread());
  TRACE_EVENT_INSTANT("cc,benchmark", "ProxyImpl::ReadyToActivate",
                      [&](perfetto::EventContext ctx) {
                        EmitMainFramePipelineStep(
                            ctx, host_impl_->sync_tree()->trace_id(),
                            perfetto::protos::pbzero::MainFramePipeline::Step::
                                READY_TO_ACTIVATE);
                      });
  scheduler_->NotifyReadyToActivate();
}

bool ProxyImpl::IsReadyToActivate() {
  DCHECK(IsImplThread());
  return scheduler_->IsReadyToActivate();
}

void ProxyImpl::NotifyReadyToDraw() {
  TRACE_EVENT0("cc", "ProxyImpl::NotifyReadyToDraw");
  DCHECK(IsImplThread());
  scheduler_->NotifyReadyToDraw();
}

void ProxyImpl::SetNeedsRedrawOnImplThread() {
  TRACE_EVENT0("cc", "ProxyImpl::SetNeedsRedrawOnImplThread");
  DCHECK(IsImplThread());
  scheduler_->SetNeedsRedraw();
}

void ProxyImpl::SetNeedsOneBeginImplFrameOnImplThread() {
  TRACE_EVENT0("cc", "ProxyImpl::SetNeedsOneBeginImplFrameOnImplThread");
  DCHECK(IsImplThread());
  scheduler_->SetNeedsOneBeginImplFrame();
}

void ProxyImpl::SetNeedsPrepareTilesOnImplThread() {
  DCHECK(IsImplThread());
  scheduler_->SetNeedsPrepareTiles();
}

void ProxyImpl::SetNeedsCommitOnImplThread(BeginMainFrameReason reason,
                                           bool urgent,
                                           bool unthrottled) {
  set_begin_main_frame_reason(reason);
  TRACE_EVENT0("cc", "ProxyImpl::SetNeedsCommitOnImplThread");
  DCHECK(IsImplThread());
  scheduler_->SetNeedsBeginMainFrame(urgent, unthrottled);
}

void ProxyImpl::SetVideoNeedsBeginFrames(bool needs_begin_frames) {
  TRACE_EVENT1("cc", "ProxyImpl::SetVideoNeedsBeginFrames",
               "needs_begin_frames", needs_begin_frames);
  DCHECK(IsImplThread());
  // In tests the layer tree is destroyed after the scheduler is.
  if (scheduler_)
    scheduler_->SetVideoNeedsBeginFrames(needs_begin_frames);
}

void ProxyImpl::DidChangeBeginFrameSourcePaused(bool paused) {
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::DidChangeBeginFrameSourcePaused,
                                proxy_main_weak_ptr_, paused));
}

bool ProxyImpl::IsInsideDraw() {
  return inside_draw_;
}

void ProxyImpl::RenewTreePriority() {
  DCHECK(IsImplThread());

  const bool precise_scrolling_in_progress =
      host_impl_->GetActivelyScrollingType() == ActivelyScrollingType::kPrecise;

  const bool avoid_entering_smoothness =
      (base::FeatureList::IsEnabled(
           features::kNewContentForCheckerboardedScrolls) &&
       host_impl_->PrioritizeNewContentDueToCheckerboarding()) ||
      (precise_scrolling_in_progress &&
       host_impl_->IsCurrentScrollMainRepainted());

  const bool non_scroll_interaction_in_progress =
      host_impl_->IsPinchGestureActive() ||
      host_impl_->page_scale_animation_active();

  bool is_current_scroll_main_painted =
      host_impl_->IsCurrentScrollMainRepainted();

  // Schedule expiration if smoothness currently takes priority.
  if ((non_scroll_interaction_in_progress || precise_scrolling_in_progress) &&
      !avoid_entering_smoothness) {
    smoothness_priority_expiration_notifier_.Schedule();
  }

  // We use the same priority for both trees by default.
  TreePriority tree_priority = SAME_PRIORITY_FOR_BOTH_TREES;

  // Smoothness takes priority if we have an expiration for it scheduled.
  if (smoothness_priority_expiration_notifier_.HasPendingNotification()) {
    tree_priority = SMOOTHNESS_TAKES_PRIORITY;
  }

  // New content takes priority in certain cases:
  // - When ui resources have been evicted.
  // - When the viewport is 0x0 (may be invalid/unset?)
  // - When the active scroll gesture requires main-thread repainting for the
  //   scroll offset change to be visible.
  if (host_impl_->active_tree()->GetDeviceViewport().size().IsEmpty() ||
      host_impl_->EvictedUIResourcesExist() || is_current_scroll_main_painted) {
    // Once we enter NEW_CONTENTS_TAKES_PRIORITY mode, visible tiles on active
    // tree might be freed. We need to set RequiresHighResToDraw to ensure that
    // high res tiles will be required to activate pending tree.
    host_impl_->SetRequiresHighResToDraw();
    tree_priority = NEW_CONTENT_TAKES_PRIORITY;
  }

  host_impl_->SetTreePriority(tree_priority);

  // Only put the scheduler in impl latency prioritization mode if we don't
  // have a scroll listener. This gives the scroll listener a better chance of
  // handling scroll updates within the same frame. The tree itself is still
  // kept in prefer smoothness mode to allow checkerboarding.
  scheduler_->SetTreePrioritiesAndScrollState(tree_priority,
                                              is_current_scroll_main_painted);
}

void ProxyImpl::PostDelayedAnimationTaskOnImplThread(base::OnceClosure task,
                                                     base::TimeDelta delay) {
  DCHECK(IsImplThread());
  task_runner_provider_->ImplThreadTaskRunner()->PostDelayedTask(
      FROM_HERE, std::move(task), delay);
}

void ProxyImpl::DidActivateSyncTree() {
  TRACE_EVENT0("cc", "ProxyImpl::DidActivateSyncTreeOnImplThread");
  DCHECK(IsImplThread());

  if (activation_completion_event_) {
    TRACE_EVENT_INSTANT("cc", "ReleaseCommitbyActivation");
    activation_completion_event_ = nullptr;
  }
}

void ProxyImpl::DidPrepareTiles() {
  DCHECK(IsImplThread());
  scheduler_->DidPrepareTiles();
}

void ProxyImpl::DidCompletePageScaleAnimationOnImplThread() {
  DCHECK(IsImplThread());
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::DidCompletePageScaleAnimation,
                                proxy_main_weak_ptr_));
}

void ProxyImpl::OnDrawForLayerTreeFrameSink(bool resourceless_software_draw,
                                            bool skip_draw) {
  DCHECK(IsImplThread());
  scheduler_->OnDrawForLayerTreeFrameSink(resourceless_software_draw,
                                          skip_draw);
}

void ProxyImpl::SetNeedsImplSideInvalidation(
    bool needs_first_draw_on_activation) {
  DCHECK(IsImplThread());
  scheduler_->SetNeedsImplSideInvalidation(needs_first_draw_on_activation);
}

void ProxyImpl::NotifyImageDecodeRequestFinished(int request_id,
                                                 bool speculative,
                                                 bool decode_succeeded) {
  DCHECK(IsImplThread());
  if (base::FeatureList::IsEnabled(
          features::kSendExplicitDecodeRequestsImmediately)) {
    MainThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::BindOnce(&ProxyMain::NotifyImageDecodeRequestFinished,
                       proxy_main_weak_ptr_, request_id, decode_succeeded));
  } else {
    SetNeedsCommitOnImplThread(BeginMainFrameReason::kOther,
                               /* urgent= */ false, /* unthrottled= */ false);
  }
}

void ProxyImpl::NotifyTransitionRequestFinished(
    uint32_t sequence_id,
    const viz::ViewTransitionElementResourceRects& rects) {
  DCHECK(IsImplThread());
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::NotifyTransitionRequestFinished,
                                proxy_main_weak_ptr_, sequence_id, rects));
}

void ProxyImpl::DidPresentCompositorFrameOnImplThread(
    uint32_t frame_token,
    PresentationTimeCallbackBuffer::PendingCallbacks activated,
    const viz::FrameTimingDetails& details) {
  host_impl_->NotifyDidPresentCompositorFrameOnImplThread(
      frame_token, std::move(activated.compositor_successful_callbacks),
      details);

  MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::BindOnce(&ProxyMain::DidPresentCompositorFrame,
                     proxy_main_weak_ptr_, frame_token,
                     std::move(activated.main_callbacks),
                     std::move(activated.main_successful_callbacks), details));
  if (scheduler_)
    scheduler_->DidPresentCompositorFrame(frame_token, details);
}

void ProxyImpl::NotifyAnimationWorkletStateChange(
    AnimationWorkletMutationState state,
    ElementListType element_list_type) {
  DCHECK(IsImplThread());
  Scheduler::AnimationWorkletState animation_worklet_state =
      (state == AnimationWorkletMutationState::STARTED)
          ? Scheduler::AnimationWorkletState::PROCESSING
          : Scheduler::AnimationWorkletState::IDLE;
  Scheduler::TreeType tree_type = (element_list_type == ElementListType::ACTIVE)
                                      ? Scheduler::TreeType::ACTIVE
                                      : Scheduler::TreeType::PENDING;
  scheduler_->NotifyAnimationWorkletStateChange(animation_worklet_state,
                                                tree_type);
}

void ProxyImpl::NotifyPaintWorkletStateChange(
    Scheduler::PaintWorkletState state) {
  DCHECK(IsImplThread());
  scheduler_->NotifyPaintWorkletStateChange(state);
}

void ProxyImpl::NotifyCompositorMetricsTrackerResults(
    CustomTrackerResults results) {
  DCHECK(IsImplThread());
  MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::BindOnce(&ProxyMain::NotifyCompositorMetricsTrackerResults,
                     proxy_main_weak_ptr_, std::move(results)));
}

void ProxyImpl::DidObserveFirstScrollDelay(
    int source_frame_number,
    base::TimeDelta first_scroll_delay,
    base::TimeTicks first_scroll_timestamp) {
  DCHECK(IsImplThread());
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::DidObserveFirstScrollDelay,
                                proxy_main_weak_ptr_, source_frame_number,
                                first_scroll_delay, first_scroll_timestamp));
}

bool ProxyImpl::WillBeginImplFrame(const viz::BeginFrameArgs& args) {
  DCHECK(IsImplThread());
  return host_impl_->WillBeginImplFrame(args);
}

void ProxyImpl::DidFinishImplFrame(
    const viz::BeginFrameArgs& last_activated_args) {
  DCHECK(IsImplThread());
  host_impl_->DidFinishImplFrame(last_activated_args);
}

void ProxyImpl::DidNotProduceFrame(const viz::BeginFrameAck& ack,
                                   FrameSkippedReason reason) {
  DCHECK(IsImplThread());
  host_impl_->DidNotProduceFrame(ack, reason);
}

void ProxyImpl::WillNotReceiveBeginFrame() {
  DCHECK(IsImplThread());
  host_impl_->DidNotNeedBeginFrame();
}

void ProxyImpl::ScheduledActionSendBeginMainFrame(
    const viz::BeginFrameArgs& args) {
  DCHECK(IsImplThread());

  benchmark_instrumentation::ScopedBeginFrameTask begin_frame_task(
      benchmark_instrumentation::kSendBeginFrame,
      args.frame_id.sequence_number);
  std::unique_ptr<BeginMainFrameAndCommitState> begin_main_frame_state(
      new BeginMainFrameAndCommitState);
  begin_main_frame_state->begin_frame_args = args;
  DCHECK(!data_for_commit_ || data_for_commit_->unsafe_state->mutator_host);
  begin_main_frame_state->commit_data = host_impl_->ProcessCompositorDeltas(
      data_for_commit_ ? data_for_commit_->unsafe_state->mutator_host
                       : nullptr);
  begin_main_frame_state->completed_image_decode_requests =
      host_impl_->TakeCompletedImageDecodeRequests();
  DCHECK(!base::FeatureList::IsEnabled(
             features::kSendExplicitDecodeRequestsImmediately) ||
         begin_main_frame_state->completed_image_decode_requests.empty());
  begin_main_frame_state->mutator_events = host_impl_->TakeMutatorEvents();
  begin_main_frame_state->active_sequence_trackers =
      host_impl_->FrameSequenceTrackerActiveTypes();
  begin_main_frame_state->evicted_ui_resources =
      host_impl_->EvictedUIResourcesExist();
  begin_main_frame_state->reason = begin_main_frame_reason_;
  begin_main_frame_state->consecutive_no_damage_main_frames =
      consecutive_no_damage_main_frames();
  begin_main_frame_reason_.reset();
  host_impl_->WillSendBeginMainFrame();
  {
    TRACE_EVENT_INSTANT(
        "cc,benchmark", "SendBeginMainFrame", [&](perfetto::EventContext ctx) {
          auto* pipeline = EmitMainFramePipelineStep(
              ctx, begin_main_frame_state->trace_id,
              perfetto::protos::pbzero::MainFramePipeline::Step::
                  SEND_BEGIN_MAIN_FRAME);

          auto* begin_frame_id = pipeline->set_begin_frame_id();
          begin_frame_id->set_sequence_number(args.frame_id.sequence_number);
          begin_frame_id->set_source_id(args.frame_id.source_id);
        });
  }
  MainThreadTaskRunner()->PostTask(
      FROM_HERE,
      base::BindOnce(&ProxyMain::BeginMainFrame, proxy_main_weak_ptr_,
                     std::move(begin_main_frame_state)));
  devtools_instrumentation::DidRequestMainThreadFrame(layer_tree_host_id_);
}

DrawResult ProxyImpl::ScheduledActionDrawIfPossible() {
  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionDraw");
  DCHECK(IsImplThread());

  // The scheduler should never generate this call when it can't draw.
  DCHECK(host_impl_->CanDraw());

  bool forced_draw = false;
  return DrawInternal(forced_draw);
}

DrawResult ProxyImpl::ScheduledActionDrawForced() {
  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionDrawForced");
  DCHECK(IsImplThread());
  bool forced_draw = true;
  return DrawInternal(forced_draw);
}

void ProxyImpl::ScheduledActionCommit() {
  TRACE_EVENT(
      "cc,benchmark", "ProxyImpl::Commit", [&](perfetto::EventContext ctx) {
        EmitMainFramePipelineStep(
            ctx, data_for_commit_->commit_state->trace_id,
            perfetto::protos::pbzero::MainFramePipeline::Step::COMMIT_ON_IMPL);
      });
  DCHECK(IsImplThread());
  DCHECK(data_for_commit_.get());
  DCHECK(data_for_commit_->IsValid());

  auto* commit_state = data_for_commit_->commit_state.get();
  auto* unsafe_state = data_for_commit_->unsafe_state.get();
  host_impl_->BeginCommit(commit_state->source_frame_number,
                          commit_state->trace_id);
  host_impl_->FinishCommit(*commit_state, *unsafe_state);
  base::TimeTicks finish_time = base::TimeTicks::Now();
  if (data_for_commit_->commit_timestamps)
    data_for_commit_->commit_timestamps->finish = finish_time;
  data_for_commit_->commit_completion_event->SetFinishTime(finish_time);

  if (commit_state->commit_waits_for_activation) {
    // For some layer types in impl-side painting, the commit is held until the
    // sync tree is activated.  It's also possible that the sync tree has
    // already activated if there was no work to be done.
    TRACE_EVENT_INSTANT("cc", "HoldCommit");
    activation_completion_event_ =
        std::move(data_for_commit_->commit_completion_event);
  }

  data_for_commit_.reset();
}

void ProxyImpl::ScheduledActionPostCommit() {
  DCHECK(IsImplThread());

  // This is run as a separate step from commit because it can be time-consuming
  // and ought not delay sending the next BeginMainFrame.
  host_impl_->CommitComplete();
}

void ProxyImpl::ScheduledActionActivateSyncTree() {
  if (host_impl_->sync_tree() &&
      host_impl_->sync_tree()->source_frame_number() !=
          host_impl_->active_tree()->source_frame_number()) {
    next_frame_is_newly_committed_frame_ = true;
  }
  DCHECK(IsImplThread());
  host_impl_->ActivateSyncTree();
}

void ProxyImpl::ScheduledActionBeginLayerTreeFrameSinkCreation() {
  TRACE_EVENT0("cc",
               "ProxyImpl::ScheduledActionBeginLayerTreeFrameSinkCreation");
  DCHECK(IsImplThread());
  MainThreadTaskRunner()->PostTask(
      FROM_HERE, base::BindOnce(&ProxyMain::RequestNewLayerTreeFrameSink,
                                proxy_main_weak_ptr_));
}

void ProxyImpl::ScheduledActionPrepareTiles() {
  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionPrepareTiles");
  DCHECK(IsImplThread());
  host_impl_->PrepareTiles();
}

void ProxyImpl::ScheduledActionInvalidateLayerTreeFrameSink(bool needs_redraw) {
  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionInvalidateLayerTreeFrameSink");
  DCHECK(IsImplThread());
  host_impl_->InvalidateLayerTreeFrameSink(needs_redraw);
}

void ProxyImpl::ScheduledActionPerformImplSideInvalidation() {
  TRACE_EVENT0("cc", "ProxyImpl::ScheduledActionPerformImplSideInvalidation");
  DCHECK(IsImplThread());
  host_impl_->InvalidateContentOnImplSide();
}

void ProxyImpl::OnBeginImplFrameDeadline() {
  DCHECK(IsImplThread());
  host_impl_->OnBeginImplFrameDeadline();
}

DrawResult ProxyImpl::DrawInternal(bool forced_draw) {
  DCHECK(IsImplThread());
  DCHECK(host_impl_.get());

  TRACE_EVENT(
      "cc,benchmark", "MainFrame.Draw", [&](perfetto::EventContext ctx) {
        auto* pipeline = EmitMainFramePipelineStep(
            ctx, host_impl_->active_tree()->trace_id(),
            perfetto::protos::pbzero::MainFramePipeline::Step::DRAW);
        if (next_frame_is_newly_committed_frame_) {
          viz::BeginFrameId frame_id =
              host_impl_->CurrentBeginFrameArgs().frame_id;
          auto* first_draw_frame_id =
              pipeline->set_last_begin_frame_id_during_first_draw();
          first_draw_frame_id->set_source_id(frame_id.source_id);
          first_draw_frame_id->set_sequence_number(frame_id.sequence_number);
        }
      });

  base::AutoReset<bool> mark_inside(&inside_draw_, true);

  // This method is called on a forced draw, regardless of whether we are able
  // to produce a frame, as the calling site on main thread is blocked until its
  // request completes, and we signal completion here. If CanDraw() is false, we
  // will indicate success=false to the caller, but we must still signal
  // completion to avoid deadlock.

  // We guard PrepareToDraw() with CanDraw() because it always returns a valid
  // frame, so can only be used when such a frame is possible. Since
  // DrawLayers() depends on the result of PrepareToDraw(), it is guarded on
  // CanDraw() as well.

  FrameData frame;
  frame.begin_frame_ack = scheduler_->CurrentBeginFrameAckForActiveTree();
  frame.origin_begin_main_frame_args =
      scheduler_->last_activate_origin_frame_args();
  bool draw_frame = false;

  DrawResult result;
  {
    TRACE_EVENT(
        "viz,benchmark,graphics.pipeline", "Graphics.Pipeline",
        perfetto::Flow::Global(host_impl_->CurrentBeginFrameArgs().trace_id),
        [&](perfetto::EventContext ctx) {
          base::TaskAnnotator::EmitTaskTimingDetails(ctx);
          auto* event = ctx.event<perfetto::protos::pbzero::ChromeTrackEvent>();
          auto* data = event->set_chrome_graphics_pipeline();
          data->set_step(perfetto::protos::pbzero::ChromeGraphicsPipeline::
                             StepName::STEP_GENERATE_COMPOSITOR_FRAME);
          data->set_surface_frame_trace_id(
              host_impl_->CurrentBeginFrameArgs().trace_id);
        });

    if (host_impl_->CanDraw()) {
      result = host_impl_->PrepareToDraw(&frame);
      draw_frame = forced_draw || result == DrawResult::kSuccess;
    } else {
      result = DrawResult::kAbortedCantDraw;
    }

    if (draw_frame) {
      if (std::optional<SubmitInfo> submit_info =
              host_impl_->DrawLayers(&frame)) {
        DCHECK_NE(frame.frame_token, viz::kInvalidFrameToken);
        // Drawing implies we submitted a frame to the LayerTreeFrameSink.
        scheduler_->DidSubmitCompositorFrame(submit_info.value());
      }
      result = DrawResult::kSuccess;
    } else {
      DCHECK_NE(DrawResult::kSuccess, result);
    }
  }

  host_impl_->DidDrawAllLayers(frame);

  bool start_ready_animations = draw_frame;
  host_impl_->UpdateAnimationState(start_ready_animations);

  // Tell the main thread that the frame was drawn.
  if (next_frame_is_newly_committed_frame_) {
    next_frame_is_newly_committed_frame_ = false;
    MainThreadTaskRunner()->PostTask(
        FROM_HERE,
        base::BindOnce(&ProxyMain::DidCommitAndDrawFrame, proxy_main_weak_ptr_,
                       host_impl_->active_tree()->source_frame_number()));
  }

  // The tile visibility/priority of the pending tree needs to be updated so
  // that it doesn't get activated before the raster is complete. But this needs
  // to happen after the draw, off of the critical path to draw.
  if (host_impl_->pending_tree()) {
    host_impl_->pending_tree()->UpdateDrawProperties(
        /*update_tiles=*/true, /*update_image_animation_controller=*/true);
  }

  DCHECK_NE(DrawResult::kInvalidResult, result);
  return result;
}

bool ProxyImpl::IsImplThread() const {
  return task_runner_provider_->IsImplThread();
}

bool ProxyImpl::IsMainThreadBlocked() const {
  return task_runner_provider_->IsMainThreadBlocked();
}

base::SingleThreadTaskRunner* ProxyImpl::MainThreadTaskRunner() {
  return task_runner_provider_->MainThreadTaskRunner();
}

void ProxyImpl::QueueImageDecodeOnImpl(int request_id,
                                       std::unique_ptr<DrawImage> image,
                                       bool speculative) {
  host_impl_->QueueImageDecode(request_id, *image, speculative);
}

void ProxyImpl::SetSourceURL(ukm::SourceId source_id, const GURL& url) {
  DCHECK(IsImplThread());
  host_impl_->SetActiveURL(url, source_id);
}

void ProxyImpl::ClearHistory() {
  DCHECK(IsImplThread());
  scheduler_->ClearHistory();
}

size_t ProxyImpl::CommitDurationSampleCountForTesting() const {
  return scheduler_->CommitDurationSampleCountForTesting();  // IN-TEST
}

void ProxyImpl::SetRenderFrameObserver(
    std::unique_ptr<RenderFrameMetadataObserver> observer) {
  host_impl_->SetRenderFrameObserver(std::move(observer));
}

void ProxyImpl::DetachInputDelegateAndRenderFrameObserver(
    CompletionEvent* completion_event) {
  host_impl_->DetachInputDelegateAndRenderFrameObserver();
  completion_event->Signal();
}

ProxyImpl::DataForCommit::DataForCommit(
    std::unique_ptr<ScopedCommitCompletionEvent> commit_completion_event,
    std::unique_ptr<CommitState> commit_state,
    const ThreadUnsafeCommitState* unsafe_state,
    CommitTimestamps* commit_timestamps)
    : commit_completion_event(std::move(commit_completion_event)),
      commit_state(std::move(commit_state)),
      unsafe_state(unsafe_state),
      commit_timestamps(commit_timestamps) {}

ProxyImpl::DataForCommit::~DataForCommit() = default;

bool ProxyImpl::DataForCommit::IsValid() const {
  return commit_completion_event.get() && commit_state.get() && unsafe_state;
}


void ProxyImpl::SetRequestHighFramerate(bool flag) {
  scheduler_->SetRequestHighFramerate(flag);
}

void ProxyImpl::NotifyNewLocalSurfaceIdExpectedWhilePaused() {
  host_impl_->NotifyNewLocalSurfaceIdExpectedWhilePaused();
}

}  // namespace cc