Test client hint behavior with setUserAgentOverride.
Testing without specifying userAgentMetadata
navigator.userAgent == Custombrowser
brands == []
is mobile?false
Missing header:sec-ch-ua
Missing header:sec-ch-ua-arch
Missing header:sec-ch-ua-bitness
Missing header:sec-ch-ua-full-version
Missing header:sec-ch-ua-full-version-list
Missing header:sec-ch-ua-platform
Missing header:sec-ch-ua-platform-version
Missing header:sec-ch-ua-mobile
Missing header:sec-ch-ua-model
Missing header:sec-ch-ua-wow64
Missing header:sec-ch-ua-form-factors

Testing with specifying userAgentMetadata
navigator.userAgent == Ferrum Typewriter
brands == [{"brand":"Ferrum","version":"42.0"},{"brand":"Iron","version":"3"}]
is mobile?true
{
    architecture : Electromechanical
    bitness : 64
    brands : [
        [0] : {
            brand : Ferrum
            version : 42.0
        }
        [1] : {
            brand : Iron
            version : 3
        }
    ]
    formFactors : [
        [0] : Desktop
        [1] : XR
    ]
    fullVersionList : [
        [0] : {
            brand : Ferrum
            version : 42.0.3.14159
        }
        [1] : {
            brand : Iron
            version : 3.1.4.159
        }
    ]
    mobile : true
    model : QWERTY
    platform : Typewriter
    platformVersion : 1950
    uaFullVersion : 42.0.3.14159
    wow64 : false
}
sec-ch-ua: "Ferrum";v="42.0", "Iron";v="3"
sec-ch-ua-arch: "Electromechanical"
sec-ch-ua-bitness: "64"
sec-ch-ua-full-version: "42.0.3.14159"
sec-ch-ua-full-version-list: "Ferrum";v="42.0.3.14159", "Iron";v="3.1.4.159"
sec-ch-ua-platform: "Typewriter"
sec-ch-ua-platform-version: "1950"
sec-ch-ua-mobile: ?1
sec-ch-ua-model: "QWERTY"
sec-ch-ua-wow64: ?0
sec-ch-ua-form-factors: "Desktop", "XR"

Testing with override invalid form factors
Can't specify UserAgentMetadata with invalid form factors.

Testing with specifying getHighEntropyValues
{
    architecture : Electromechanical
    brands : [
        [0] : {
            brand : Ferrum
            version : 42.0
        }
        [1] : {
            brand : Iron
            version : 3
        }
    ]
    mobile : true
    platform : Typewriter
}
sec-ch-ua: "Ferrum";v="42.0", "Iron";v="3"
sec-ch-ua-arch: "Electromechanical"
sec-ch-ua-platform: "Typewriter"
sec-ch-ua-mobile: ?1

Testing effect on navigation
sec-ch-ua: "Ferrum";v="42.0", "Iron";v="3"
sec-ch-ua-arch: "Electromechanical"
sec-ch-ua-bitness: "64"
sec-ch-ua-full-version: "42.0.3.14159"
sec-ch-ua-full-version-list: "Ferrum";v="42.0.3.14159", "Iron";v="3.1.4.159"
sec-ch-ua-platform: "Typewriter"
sec-ch-ua-platform-version: "1950"
sec-ch-ua-mobile: ?1
sec-ch-ua-model: "QWERTY"
sec-ch-ua-wow64: ?0

Testing defaulting of brand and fullVersion
navigator.userAgent == Electric Typewriter
brands == [{"brand":"content_shell","version":"999"}]
is mobile?true
{
    architecture : Electronic
    bitness : 64
    brands : [
        [0] : {
            brand : content_shell
            version : 999
        }
    ]
    formFactors : [
        [0] : Desktop
        [1] : XR
    ]
    fullVersionList : [
        [0] : {
            brand : content_shell
            version : 999.77.34.5
        }
    ]
    mobile : true
    model : With erase tape
    platform : Electric Typewriter
    platformVersion : 1970
    uaFullVersion : 999.77.34.5
    wow64 : true
}
sec-ch-ua: "content_shell";v="999"
sec-ch-ua-arch: "Electronic"
sec-ch-ua-bitness: "64"
sec-ch-ua-full-version: "999.77.34.5"
sec-ch-ua-full-version-list: "content_shell";v="999.77.34.5"
sec-ch-ua-platform: "Electric Typewriter"
sec-ch-ua-platform-version: "1970"
sec-ch-ua-mobile: ?1
sec-ch-ua-model: "With erase tape"
sec-ch-ua-wow64: ?1
sec-ch-ua-form-factors: "Desktop", "XR"