media: Add support for playback of VP8 Alpha video streams

BUG=147355
TEST=VP8 Alpha video streams play
TBR=sky

Review URL: https://chromiumcodereview.appspot.com/13886011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195339 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 840b56b..98d6829d 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -706,6 +706,13 @@
     SINGLE_VALUE_TYPE(switches::kEnableVp9Playback)
   },
   {
+    "enable-vp8-alpha-playback",
+    IDS_FLAGS_ENABLE_VP8_ALPHA_PLAYBACK_NAME,
+    IDS_FLAGS_ENABLE_VP8_ALPHA_PLAYBACK_DESCRIPTION,
+    kOsDesktop,
+    SINGLE_VALUE_TYPE(switches::kEnableVp8AlphaPlayback)
+  },
+  {
     "enable-managed-users",
     IDS_FLAGS_ENABLE_LOCALLY_MANAGED_USERS_NAME,
     IDS_FLAGS_ENABLE_LOCALLY_MANAGED_USERS_DESCRIPTION,