CC Animations: Make LayerAnimationController creation optional

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index f3f6489daee1f0e3dec61487b979322f8e8fe52d..d9321f222e1af0fc1e7b4cc0bac83922cc1fdf8d 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -230,7 +230,7 @@ void RenderWidgetCompositor::Initialize() {
       !cmd->HasSwitch(cc::switches::kDisableThreadedAnimation);
   settings.use_display_lists = cmd->HasSwitch(switches::kEnableSlimmingPaint);
   if (cmd->HasSwitch(switches::kEnableCompositorAnimationTimelines)) {
-    settings.use_compositor_animation_timelines = true;
+    settings.hud_layer_settings_.use_compositor_animation_timelines = true;

[piman, 2015/05/11 21:31:24]

Could you use WebLayerImpl::LayerSettings() here for
settings.hud_layer_settings_? It would keep them consistent between each other.

     blink::WebRuntimeFeatures::enableCompositorAnimationTimelines(true);
   }
   if (cmd->HasSwitch(switches::kEnableBeginFrameScheduling) &&
@@ -661,8 +661,7 @@ void RenderWidgetCompositor::didStopFlinging() {
 
 void RenderWidgetCompositor::registerForAnimations(blink::WebLayer* layer) {
   cc::Layer* cc_layer = static_cast<cc_blink::WebLayerImpl*>(layer)->layer();
-  cc_layer->layer_animation_controller()->SetAnimationRegistrar(
-      layer_tree_host_->animation_registrar());
+  cc_layer->RegisterForAnimations(layer_tree_host_->animation_registrar());
 }
 
 void RenderWidgetCompositor::registerViewportLayers(