Add chrome://flags entry to control MPEG4+AVI support.

Adds a new chrome://flags/#cros-legacy-media-formats switch so
that users can control support for MPEG4+AVI content.

The flag lifetime is set to be M120-M125, since M120 and M126
are the next two LTS releases respectively. Assuming there's
not an inordinate amount of breakage, this flag and supporting
code will be removed in M126.

R=tapted

Bug: 1491502
Change-Id: I1399a97525ccaef7e78e3fe70deb090f0c1faa91
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4939546
Commit-Queue: Trent Apted <tapted@chromium.org>
Auto-Submit: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1209967}

chrome/browser/about_flags.cc

@@ -4490,6 +4490,10 @@ const FeatureEntry kFeatureEntries[] = {
 #endif  // BUILDFLAG(IS_CHROMEOS_ASH)
 
 #if BUILDFLAG(IS_CHROMEOS)
+    {"cros-legacy-media-formats",
+     flag_descriptions::kCrOSLegacyMediaFormatsName,
+     flag_descriptions::kCrOSLegacyMediaFormatsDescription, kOsCrOS | kOsLacros,
+     FEATURE_VALUE_TYPE(media::kCrOSLegacyMediaFormats)},
     {"disable-idle-sockets-close-on-memory-pressure",
      flag_descriptions::kDisableIdleSocketsCloseOnMemoryPressureName,
      flag_descriptions::kDisableIdleSocketsCloseOnMemoryPressureDescription,

chrome/browser/flag-metadata.json

@@ -1440,6 +1440,11 @@
     "owners": [ "aluh", "homi" ],
     "expiry_milestone": 130
   },
+  {
+    "name": "cros-legacy-media-formats",
+    "owners": [ "dalecurtis", "tapted" ],
+    "expiry_milestone": 125
+  },
   {
     "name": "cros-libassistant-v2-migration",
     "owners": ["wutao@chromium.com", "assistive-eng@google.com"],

chrome/browser/flag_descriptions.cc

@@ -165,6 +165,13 @@ const char kContentLanguagesInLanguagePickerDescription[] =
     "Enables bringing user's content languages that are translatable to the "
     "top of the list with all languages shown in the translate menu";
 
+#if BUILDFLAG(IS_CHROMEOS)
+const char kCrOSLegacyMediaFormatsName[] = "Legacy media format support";
+const char kCrOSLegacyMediaFormatsDescription[] =
+    "Controls support for uncommon legacy media formats: AVI containers and "
+    "MPEG4 video streams.";
+#endif
+
 const char kCustomizeChromeColorExtractionName[] =
     "Customize Chrome Color Extraction";
 const char kCustomizeChromeColorExtractionDescription[] =

chrome/browser/flag_descriptions.h

@@ -134,6 +134,11 @@ extern const char kClipboardMaximumAgeDescription[];
 extern const char kContentLanguagesInLanguagePickerName[];
 extern const char kContentLanguagesInLanguagePickerDescription[];
 
+#if BUILDFLAG(IS_CHROMEOS)
+extern const char kCrOSLegacyMediaFormatsName[];
+extern const char kCrOSLegacyMediaFormatsDescription[];
+#endif
+
 extern const char kCustomizeChromeColorExtractionName[];
 extern const char kCustomizeChromeColorExtractionDescription[];
 

tools/metrics/histograms/enums.xml

@@ -63248,6 +63248,7 @@ from previous Chrome versions.
       label="DesktopPWAsAdditionalWindowingControls:enabled"/>
   <int value="-981354827" label="SupportSearchSuggestionForPrerender2:enabled"/>
   <int value="-981237342" label="SyncUSSAutofillWalletMetadata:disabled"/>
+  <int value="-981090414" label="CrOSLegacyMediaFormats:enabled"/>
   <int value="-981033001" label="TabScrollingButtonPosition:enabled"/>
   <int value="-980889204" label="SharingRenameDevices:enabled"/>
   <int value="-980475527" label="DevToolsTabTarget:disabled"/>
@@ -68633,6 +68634,7 @@ from previous Chrome versions.
   <int value="1665349789" label="spurious-power-button-window"/>
   <int value="1665400247" label="OsSettingsDeepLinking:enabled"/>
   <int value="1665430464" label="force-control-face-ae"/>
+  <int value="1666226008" label="CrOSLegacyMediaFormats:disabled"/>
   <int value="1666933104" label="TabStripStartupRefactoring:enabled"/>
   <int value="1667533501" label="SameAppWindowCycle:disabled"/>
   <int value="1667584730" label="WebXR:disabled"/>