GMC: Add global media controls to chrome://flags

Bug: 979248
Change-Id: I6d87fc3944490ae082ee76a8b55c76ea42ab924c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1680862
Commit-Queue: Tommy Steimel <[email protected]>
Reviewed-by: Mounir Lamouri <[email protected]>
Cr-Commit-Position: refs/heads/master@{#673769}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index f23f1777..44efc580 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -4033,6 +4033,13 @@
      flag_descriptions::kEnableSyncUSSNigoriDescription, kOsAll,
      FEATURE_VALUE_TYPE(switches::kSyncUSSNigori)},
 
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+    {"global-media-controls", flag_descriptions::kGlobalMediaControlsName,
+     flag_descriptions::kGlobalMediaControlsDescription,
+     kOsWin | kOsMac | kOsLinux,
+     FEATURE_VALUE_TYPE(media::kGlobalMediaControls)},
+#endif  // defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+
     // NOTE: Adding a new flag requires adding a corresponding entry to enum
     // "LoginCustomFlags" in tools/metrics/histograms/enums.xml. See "Flag
     // Histograms" in tools/metrics/histograms/README.md (run the