CC Animations: Make LayerAnimationController creation optional

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 6f10725b08ff536bc30d8b4c5bb05a8198b85856..82e3a24de798c0acb6ee063fbbf0ed7d7513b224 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -58,9 +58,11 @@ class CopyOutputRequest;
 class LayerAnimationEventObserver;
 class LayerClient;
 class LayerImpl;
+class LayerSettings;
 class LayerTreeHost;
 class LayerTreeHostCommon;
 class LayerTreeImpl;
+class LayerTreeSettings;
 class PriorityCalculator;
 class RenderingStatsInstrumentation;
 class ResourceUpdateQueue;
@@ -84,7 +86,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
     INVALID_ID = -1,
   };
 
-  static scoped_refptr<Layer> Create();
+  static scoped_refptr<Layer> Create(const LayerSettings& settings);
 
   int id() const { return layer_id_; }
 
@@ -424,10 +426,12 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
       scoped_refptr<LayerAnimationController> controller);
 
   void set_layer_animation_delegate(AnimationDelegate* delegate) {
+    DCHECK(layer_animation_controller_);
     layer_animation_controller_->set_layer_animation_delegate(delegate);
   }
 
   bool HasActiveAnimation() const;
+  void RegisterForAnimations(AnimationRegistrar* registrar);
 
   void AddLayerAnimationEventObserver(
       LayerAnimationEventObserver* animation_observer);
@@ -558,7 +562,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
   friend class TreeSynchronizer;
   ~Layer() override;
 
-  Layer();
+  explicit Layer(const LayerSettings& settings);
 
   // These SetNeeds functions are in order of severity of update:
   //