Add a comment for Linux video decode acceleration.

BUG=137247

Review URL: https://chromiumcodereview.appspot.com/10821049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148659 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/render_view_impl.cc

@@ -2375,6 +2375,8 @@ WebMediaPlayer* RenderViewImpl::createMediaPlayer(
     collection->AddAudioRenderer(audio_renderer);
   }
 
+  // Accelerated video decode is not enabled by default on Linux.
+  // crbug.com/137247
   bool use_accelerated_video_decode = false;
 #if defined(OS_CHROMEOS) || defined(OS_WIN)
   use_accelerated_video_decode = true;