nafisabedin@google.com yfriedman@chromium.org Records true if the Google Search Results Page is ever visited during a session for a given ChromeTabbedActivity, false otherwise. Recorded when an UMA Session ends. asvitkine@chromium.org src/base/metrics/OWNERS Sum of this metric yields the total time Chrome was running in the background. A single session may be represented by multiple values, so that this histogram is always present in an uploaded log that represents background activity. Android-only. avi@chromium.org chrome-mac-dev@google.com The total time a Chrome browser window spends in fullscreen. Content fullscreen is not represented. Records are capped at 24 hours. The metric is recorded when a browser window exits fullscreen or after 24 hours has elapsed, whichever comes first. This includes quitting the browser while in fullscreen. Mac-only. sammon@google.com dljames@chromium.org The duration of the AppendCommands operation for {SessionType} sessions ({EncryptedStatus}), when the truncate parameter was {Slice}. AppendCommands is typically called periodically during a browser session to save the current session state. sammon@google.com dljames@chromium.org The size of the file written by CommandStorageBackend for {SessionType} sessions ({EncryptedStatus}), when the truncate parameter was {Slice}. Recorded each time the file is written successfully. The file is written periodically during a browser session to save the current session state. sammon@google.com dljames@chromium.org The result of the AppendCommands operation for {SessionType} sessions ({EncryptedStatus}), when the truncate parameter was {Slice}. AppendCommands is typically called periodically during a browser session to save the current session state. sammon@google.com dljames@chromium.org The duration of the ReadLastSessionCommands operation for {SessionType} sessions ({EncryptedStatus}). ReadLastSessionCommands is typically called during browser startup to restore the previous session state. sammon@google.com dljames@chromium.org The result of the ReadLastSessionCommands operation for {SessionType} sessions ({EncryptedStatus}). ReadLastSessionCommands is typically called during browser startup to restore the previous session state. sammon@google.com dljames@chromium.org Records when the encrypted backend is accessed before it has been initialized. The enum indicates which operation attempted the access. sammon@google.com dljames@chromium.org The result of comparing the commands read from the cleartext and encrypted backends. Recorded after the commands are read from the cleartext and encrypted backends when the feature flag allows. sammon@google.com dljames@chromium.org The duration from when OSCryptAsync::GetInstance is requested by a CommandStorageManager to when an Encryptor is received via the OnEncryptorReady callback. An Encryptor is only requested if ShouldWriteEncryptedFiles() is true; this metric is not recorded otherwise. Note that there may be multiple CommandStorageManagers (e.g. for different session types and different profiles), so this metric may be recorded multiple times per app startup. gambard@chromium.org sdefresne@chromium.org Records the difference between the highest restored SessionID and the value of the pref used for the next SessionID. If the difference is negative, 0 is recorded (0 means there is no problem, the session ID's pref was correctly restored). Having a value > 0 means that there has been an issue and the SessionID was probably not recorded properly. This is recorded after each session restoration (so it can be recorded multiple times per run). rogerm@chromium.org src/base/metrics/OWNERS Warning: This histogram is broken on Android, please use Session.IsActive2 there instead. Was a browsing session active when the UMA record was captured? This metric is recorded with every UMA log upload when the session tracker is running (which, in principle, should always be the case). This metric is NOT recorded in logs that reflect information from a previous session (i.e., "stability logs" or "persistent UMA" data related to the previous session but not uploaded during the previous session). Recorded on Android, iOS, Windows, Mac, and Linux. For information on what's considered "active", see the histogram description for Session.TotalDuration. rogerm@chromium.org src/base/metrics/OWNERS Fixes an issue with Session.IsActive where foreground Sessions were not marked as active on Android. Was a browsing session active when the UMA record was captured? This metric is recorded with every UMA log upload when the session tracker is running (which, in principle, should always be the case). This metric is NOT recorded in logs that reflect information from a previous session (i.e., "stability logs" or "persistent UMA" data related to the previous session but not uploaded during the previous session). Recorded only on Android. For information on what's considered "active", see the histogram description for Session.TotalDuration. victortan@chromium.org chrome-analysis-team@google.com The duration the screen was locked (OS-level lock) while Chrome was running. Recorded when the screen is unlocked or the session ends. victortan@chromium.org chrome-analysis-team@google.com Records the combination of reasons a potential restart during OS lock screen was blocked, or 'None' if it was viable. Recorded when the zero-window state ends while an update is pending. The value is recorded as a bitmask of SmartRestartBlockReason flags. This histogram is sliced by the duration the OS was in the Locked state. V2: Uses refined logic for 'Unsaved form data' requiring both user interaction and a beforeunload handler. victortan@chromium.org chrome-analysis-team@google.com The duration the screen was locked (OS-level lock) while Chrome was running AND an update was pending (UpgradeDetector). Recorded when the screen is unlocked or the session ends. rohitrao@chromium.org marq@chromium.org The number of times the user changed the active tab (this can happen when manually selecting a new tab, when a pre-rendered tab is made active, when closing the current tab and the next one is selected) during the current session (launch/foregrounding to backgrounding). This histogram is only logged on iOS when the application is backgrounded. musalmaan@chromium.org koretadaniel@chromium.org Records whether the user changed the session restore setting after being shown the session restore infobar that informs the user about {SessionRestoreInfobarType}. A `true` value is recorded if the user changes the session restore setting while the infobar is shown. A `false` value is recorded if the user dismisses the infobar without changing the setting (which stops the infobar from being shown again), or the user has ignored the infobar and it has been shown a max of 3 times. This histogram is not recorded if the user changes the setting at any other time (i.e. when the session restore infobar is not showing). miketaylr@chromium.org chrome-analysis-team@google.com How did the user interact with the SessionCrashed Bubble? victortan@chromium.org chrome-analysis-team@google.com The final outcome of a Smart Restart attempt triggered by an OS Lock event, segmented by {TabCount}. victortan@chromium.org chrome-analysis-team@google.com Specific reasons that contributed to the restart protection or disallowance during an OS Lock event, segmented by {TabCount}. Multiple reasons may be logged per session. victortan@chromium.org chrome-analysis-team@google.com The amount of time remaining in the grace period when a smart restart was cancelled by the user unlocking the screen. Helps identify close calls. victortan@chromium.org chrome-analysis-team@google.com The absolute count of open tabs that had active beforeunload handlers and whose prompts would have been skipped during a warning-suppressed Smart Restart relaunch on an OS Lock event. During the initial dry-run phase, this records potential suppressions without actually triggering the restart. victortan@chromium.org chrome-analysis-team@google.com The site engagement score of each tab containing a beforeunload handler whose prompt would have been skipped during a warning-suppressed Smart Restart relaunch on an OS Lock event. During the initial dry-run phase, this records potential suppressions without actually triggering the restart. victortan@chromium.org chrome-analysis-team@google.com The percentage of open tabs that had active beforeunload handlers and whose prompts would have been skipped during a warning-suppressed Smart Restart relaunch on an OS Lock event. During the initial dry-run phase, this records potential suppressions without actually triggering the restart. victortan@chromium.org chrome-analysis-team@google.com The duration from when an upgrade was first detected until a smart restart was successfully executed on an OS Lock event. Recorded in minutes. Captures gaps up to 30 days. victortan@chromium.org chrome-analysis-team@google.com Records the outcome of a Smart Restart attempt triggered by the Zero Window state on macOS. Recorded at the end of the restart attempt timer. It identifies whether the restart was executed, cancelled by the user opening a window, or blocked by the safety policy. victortan@chromium.org chrome-analysis-team@google.com The amount of time remaining in the grace period when a smart restart was cancelled by the user opening a window. Recorded on macOS. Helps identify close calls where the browser almost restarted just as the user returned. victortan@chromium.org chrome-analysis-team@google.com The duration from when an upgrade was first detected until a smart restart was successfully executed. Recorded on macOS just before the background relaunch occurs. Captures gaps up to 7 days. asvitkine@chromium.org chrisha@chromium.org chrome-analysis-team@google.com The length of a session (launch/foregrounding to quitting/backgrounding) in milliseconds, recorded at the end of the session. See Session.TotalDurationMax1Day for the same histogram with a higher maximum value. (The one's maximum is 1 hour.) Windows/Mac/Linux: Sessions only include time a browser window is visible. Time when Chrome is visible but not with a regular browsing window will not count. For example, neither the "profile picker", which is sometimes shown at startup, nor the first-run experience flow will count as active time in Chrome when calculating Session.TotalDuration. Windows/Mac/Linux: An active session ends (i) when the user puts another app in the foreground, unless audio is playing. (The Chrome windows can still be shown. What matters is that a different app has focus.) (ii) when Chrome quits. (iii) when the screensaver turns on (again, unless audio is playing). (iv) when the user is inactive for five minutes (again, unless audio is playing). In this case (starting in M-55), that five minutes is not included in the sesson length. (v) when audio stops playing, if the user has been inactive for five minutes or Chrome is not in the foreground. Also, until M69, there was a bug that caused double-counting of some sessions. ChromeOS: not implemented. The ChromeOS histogram Platform.DailyUseTime is somewhat similar. Android: Session boundaries are wonky. Thus, only look at total duration for a client over a day; don't look at individual durations. A session ends (i) when the Chrome app leaves the foreground. This sounds obvious yet there are many subtle though common edge cases here. Going to the Android Home screen via the Home button is an obvious case. Yet, merely pressing the Recents button, even if the user reselects the Chrome app (i.e., doesn't leave the app) also ends a session. Another set of cases is the screen time-out (blanking the screen) or the lock screen. Either will cause Chrome to be considered to leave the foreground, ending the session. (ii) some in-app actions. Yes, some in-app events trigger the end of a session. Android continued: These in-app actions that trigger the end of a session can mostly be considered bugs. Cases: (a) switching to viewing Bookmarks, History, Downloads, or Settings causes the session to end. Note that switching out of those modes does not cause the end of a session, only switching in. Oddly, though the interface looks similar, switching to Recent Tabs does not trigger the end of a session. Nor does going into the tab switcher view. (b) modal pop-ups. JavaScript dialogs and other things that take focus away from the Chrome activity can cause this metric to record a session end prematurely. See: crbug.com/678276. (c) switching Chrome from as a single app in the foreground into multi-window mode. (d) switching Chrome from being one of a set of multi-window apps that are displayed to be the only app displayed. iOS: A session starts when Chrome is launched to the foreground and ends when Chrome leaves the screen. This is generally straightforward. Chrome leaves the screen when the screen goes blank or shows the lock screen, when Chrome clicks a link that opens in another app, or when the user switches to another app in the app switcher. Note that, unlike on desktop, even if Chrome is playing media in the background or in picture-in-picture mode, the session is still terminated when Chrome leaves the screen. Also note that if Chrome starts in Safe Mode, the session will only start when the user quits Safe Mode. When multiple windows are used, the session is considered ongoing as long as there is at least one foreground Chrome window. This was revised in M-89 to support multiple windows. In M-87 and M-88, nothing was logged due to a bug. Before M-86, a similar metric was recorded, with some differences in edge cases. See the old histogram description for more details. This histogram is of special interest to the chrome-analysis-team@. Do not change its semantics or retire it without talking to them first. atharvmaan@google.com chrome-desktop-ui-waterloo@google.com The length of a desktop session (launch/foregrounding to quitting/backgrounding) in milliseconds, recorded at the end of the session. For the first session of an OS-launched Chrome instance, the start time is considered to be the time of the first interactive user event rather than the actual start of the session. This excludes the time Chrome spent running without user interaction. For all other sessions, the start time is the actual session start time. This histogram is similar to Session.TotalDuration, but filters out non-interactive time at the beginning of OS-launched sessions. Unlike Session.TotalDuration, it is only recorded on desktop platforms. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com chrome-analysis-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.NotOptedInToSyncWithAccount; the only difference is the histogram bucket ranges. The amount of active browsing time that was spent with sync disabled while having a valid refresh token for the primary account. This corresponds to the case when the user did not opt in to sync, or sync is disabled due to another reason, e.g. enterprise policy. Note that auth errors are not counted here, but rather in Session.TotalDuration.NotOptedInToSyncWithAccountInAuthError. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin or sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. This histogram is of special interest to the chrome-analysis-team@ and chrome-signin-team@. Do not change its semantics or retire it without talking to them first. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com chrome-analysis-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.NotOptedInToSyncWithAccountInAuthError; the only difference is the histogram bucket ranges. The amount of active browsing time that was spent with sync disabled while having a primary account with an invalid refresh token. This corresponds to the case when the user did not opt in to sync, or sync is disabled due to another reason, e.g. enterprise policy. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin or sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. This histogram is of special interest to the chrome-analysis-team@ and chrome-signin-team@. Do not change its semantics or retire it without talking to them first. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com chrome-analysis-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.NotOptedInToSyncWithoutAccount; the only difference is the histogram bucket ranges. The amount of active browsing time that was spent with sync disabled and signed out of Chrome (no primary account or invalid token for the primary account). This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin or sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. Note: As part of crbug/1223007, we discovered this histogram was recorded for Guest and System profiles which wasn't intentional. This was fixed in M93. After launching background logging in the late February 2021 on Android, this metric started recording for instances that were running in the background, even if Chrome had never come to foreground. The bug was fixed in M92, and after that the metric is recorded only after an instance becomes foregrounded at least once. Hence a glitch is visible in the Feb-Aug 2021 data for Android. This histogram is of special interest to the chrome-analysis-team@ and chrome-signin-team@. Do not change its semantics or retire it without talking to them first. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com chrome-analysis-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.OptedInToSyncWithAccount; the only difference is the histogram bucket ranges. The total session duration (see Session.TotalDuration) that was spent with sync enabled and signed in to Chrome (valid token for the primary account). This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin or sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. This histogram is of special interest to the chrome-analysis-team@ and chrome-signin-team@. Do not change its semantics or retire it without talking to them first. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com chrome-analysis-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.OptedInToSyncWithoutAccount; the only difference is the histogram bucket ranges. The total session duration (see Session.TotalDuration) that was being spent with sync inactive due to an invalid refresh token for the primary account (a.k.a. sync in an auth error state). Note that in this state, the user has already opted in to sync previously. This corresponds to the so-called "Sync paused" state. This can for example be the case when a user, that previously opted in to sync, signed out of the web on desktop, changed their password, or otherwise invalidated their signin. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin or sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. After launching background logging in the late February 2021 on Android, this metric started recording for instances that were running in the background, even if Chrome had never come to foreground. The bug was fixed in M92, and after that the metric is recorded only after an instance becomes foregrounded at least once. Hence a glitch is visible in the Feb-Aug 2021 data for Android. This histogram is of special interest to the chrome-analysis-team@ and chrome-signin-team@. Do not change its semantics or retire it without talking to them first. robliao@chromium.org gerchiko@microsoft.com wangsongjin@microsoft.com input-dev@chromium.org Time spent in tablet mode in each session (as defined by DesktopSessionDurationTracker). Samples correspond one-to-one with Session.TotalDuration samples. This histogram should be analyzed with Session.TotalDuration. For example, the sum of this histogram divided by the sum of Session.TotalDuration is the total proportion of active browsing time spent in tablet mode. collinbaker@chromium.org top-chrome-desktop-ui@google.com Time spent in touch mode in each session (as defined by DesktopSessionDurationTracker). Samples correspond one-to-one with Session.TotalDuration samples. This histogram should be analyzed with Session.TotalDuration. For example, the sum of this histogram divided by the sum of Session.TotalDuration is the total proportion of active browsing time spent in touch mode. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.WithAccount; the only difference is the histogram bucket ranges. The total session duration (see Session.TotalDuration) that was spent with a Google account signed into the content area. The difference between the With(out)Account measurements and the Opted(In/Out)ToSyncWith(out)Account measurements is that these metrics are derived from the user's cookies, not their refresh tokens. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. This histogram is of special interest to the chrome-signin-team@. Do not change its semantics or retire it without talking to them first. bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com This histogram is in the process of being replaced with the equivalent histogram Session.TotalDurationMax1Day.WithoutAccount; the only difference is the histogram bucket ranges. The total session duration (see Session.TotalDuration) that was spent without a Google account signed into the content area. The difference between the With(out)Account measurements and the Opted(In/Out)ToSyncWith(out)Account measurements is that these metrics are derived from the user's cookies, not their refresh tokens. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. Note: As part of crbug/1223007, we discovered this histogram was recorded for Guest and System profiles which wasn't intentional. This was fixed in M93. This histogram is of special interest to the chrome-signin-team@. Do not change its semantics or retire it without talking to them first. asvitkine@chromium.org chrisha@chromium.org chrome-analysis-team@google.com The length of a session (launch/foregrounding to quitting/backgrounding) in milliseconds, recorded at the end of the session. See Session.TotalDuration for details on how the end of a session is decided. The histogram Session.TotalDuration records exactly the same values as this histogram, just with a smaller maximum value. (That one's maximum is 1 hour.) This histogram is of special interest to the chrome-analysis-team@. Do not change its semantics or retire it without talking to them first. mastiz@chromium.org msarda@chromium.org treib@chromium.org chrome-signin-team@google.com The amount of active browsing time that was spent with history sync {HistorySyncState}. History sync counts as enabled if EITHER the user opted in to sync and did not disable history, OR (on supported platforms) the user is signed-in (but not syncing) and specifically opted in to history. Either way, if history is disabled by enterprise policy, that counts as NOT enabled. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their history sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. {Profile} bsazonov@chromium.org droger@chromium.org msarda@chromium.org treib@chromium.org tschumann@chromium.org chrome-signin-team@google.com chrome-analysis-team@google.com {IdentityState} This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their signin or sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. This histogram is of special interest to the chrome-analysis-team@ and chrome-signin-team@. Do not change its semantics or retire it without talking to them first. {Profile} mastiz@chromium.org msarda@chromium.org treib@chromium.org chrome-signin-team@google.com The amount of active browsing time that was spent with "Make Searches and Browsing Better" {MsbbState}. This time is measured from when the user starts interacting with the browser until either they stopped interacting with the browser or their history sync status changes. These end-points are when the metric is emitted. For details on how "stopped interacting with the browser" is decided, see the description of Session.TotalDuration. Because a duration can end either because the user became inactive or because their status changed, the distribution of individual durations measured are unlikely to be helpful. Instead, please compare total durations. This metric is recorded on Win/Mac/Linux/iOS/Android. One caveat with this metric is that if the user has multiple profiles open at the same time, their session activity will be logged from all the profiles, instead of only from the profile that the user is using at that moment. fedegermi@google.com sdefresne@chromium.org The time spent on the main thread to restore a session as a continuous task. It's recorded every time a session is loaded (which happens on application startup or when the user re-open a recently closed windows on iPad). This includes loading the data from disk as this happens on the main thread. Large values for this histogram is indicative of jank for the user as the main thread is blocked for the duration reported in the histogram in one giant operation. justincohen@chromium.org michaeldo@chromium.org Records whether the WKWebView native session restore has any fetchers or not. Recorded each time a native session restore is attempted. justincohen@chromium.org michaeldo@chromium.org Records whether generic WKWebView native session restore succeeded in creating navigation items. Recorded each time a generic native session restore is attempted (if data exists). justincohen@chromium.org michaeldo@chromium.org Records whether WKWebView native session restore from cached data succeeded in creating navigation items. Recorded each time a cached native session restore is attempted (if data exists). justincohen@chromium.org michaeldo@chromium.org Records whether the WKWebView native session restore from cached data fetcher has data or not. Recorded each time a cached native session restore is attempted. justincohen@chromium.org michaeldo@chromium.org Records whether the generic WKWebView native session restore fetcher has data or not. Recorded each time a generic native session restore is attempted. fedegermi@google.com sdefresne@chromium.org The time spend on the main thread to save a session as a continuous task. It's recorded every time a session is saved (which is scheduled on page loads, tab changes and app backgrounding, but repeating events may be collapsed). This does not include the time spent writing the file on disk (since it is done on a background sequence). Large values for this histogram is indicative of jank for the user as the main thread is blocked for the duration reported in the histogram in one giant operation. victortan@chromium.org chrome-analysis-team@google.com The duration Chrome was running with zero open browser windows (specifically TYPE_NORMAL). Recorded when a new window is opened or Chrome quits. This metric is only recorded on macOS. victortan@chromium.org chrome-analysis-team@google.com Records the combination of reasons a potential restart with zero windows open on macOS was blocked, or 'None' if it was viable. Recorded when the zero-window state ends while an update is pending. The value is recorded as a bitmask of SmartRestartBlockReason flags. This histogram is sliced by the duration the browser was in the Zero Window state. V2: Uses refined logic for 'Unsaved form data' requiring both user interaction and a beforeunload handler. victortan@chromium.org chrome-analysis-team@google.com The duration Chrome was running with zero open browser windows (specifically TYPE_NORMAL) AND an update was pending. Recorded when a new window is opened or Chrome quits. This metric is only recorded on macOS. joenotcharles@google.com catan-team@chromium.org The reason for which attempt to record SessionRestore.ForegroundTabFirstPaint4 was deemed complete. Logged once per session restore. Warning: this histogram was expired from 2022-10-23 to 2024-02-15; data may be missing. joenotcharles@google.com catan-team@chromium.org The time from SessionRestore start until a restored tab's first paint. Recorded when a restored tab stays visible from the beginning of session restore until its first paint, and no non-restored tab is painted during that time. See SessionRestore.ForegroundTabFirstPaint4.FinishReason for when this is not recorded. Warning: this histogram was expired from 2022-10-23 to 2023-02-22; data may be missing. {SessionRestoreTabCounts} musalmaan@chromium.org koretadaniel@chromium.org Records user interaction with the session restore infobar when it is shown to inform the user about turning off session restore from browser restart. musalmaan@chromium.org koretadaniel@chromium.org Records user interaction with the session restore infobar when it is shown to inform the user about turning on session restore. creis@chromium.org chrome-security-architecture@google.com The number of times a PageState with the given non-current PageState version number was decoded during session restore. Old PageState versions with sufficiently low usage may be considered for deprecation. See page_state_serialization.cc's kCurrentVersion for documentation of each version. joenotcharles@google.com catan-team@chromium.org The number of {TabType} available to restore in a session. Logged once per session restore. Not all of the tabs in the session will ultimately be loaded. This metric has several variants with suffixes for tabs with different properties. The properties aren't mutually exclusive so the sum of all variants won't equal SessionRestore.TabCount, which covers all tabs. victortan@chromium.org chrome-analysis-team@google.com The difference between the number of tabs open before a restart and the number of tabs restored for the profile in {Type}. A positive value means tabs were lost; a negative value means tabs were gained. Logged once per session restore if a pre-restart tab count was saved. sky@chromium.org davidbienvenu@chromium.org Recorded when SessionService is shutdown (which generally corresponds to when chrome is shutdown). The count is the number of times a write error happened at a time when it could not immediately be handled. victortan@chromium.org chrome-analysis-team@google.com The difference between the number of windows open before a restart and the number of windows restored for the profile in {Type}. A positive value means windows were lost; a negative value means windows were gained. Logged once per session restore if a pre-restart window count was saved.