Turn on compositing for animations with software compositor.

R=jbauman@chromium.org, piman@chromium.org, jbauman, piman
BUG=350141

Review URL: https://codereview.chromium.org/191563003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255962 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/gpu/gpu_data_manager_impl_private.cc

@@ -795,6 +795,7 @@ void GpuDataManagerImplPrivate::UpdateRendererWebPrefs(
     prefs->force_compositing_mode = true;
     prefs->accelerated_compositing_enabled = true;
     prefs->accelerated_compositing_for_3d_transforms_enabled = true;
+    prefs->accelerated_compositing_for_animation_enabled = true;
     prefs->accelerated_compositing_for_plugins_enabled = true;
     prefs->accelerated_compositing_for_video_enabled = true;
   }