CC Animations: Make LayerAnimationController creation optional

cc/layers/layer.h

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_LAYER_H_
 #define CC_LAYERS_LAYER_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 43 matching lines @@
 class Animation;
 class AnimationDelegate;
 struct AnimationEvent;
 class CopyOutputRequest;
 class LayerAnimationEventObserver;
 class LayerClient;
 class LayerImpl;
 class LayerTreeHost;
 class LayerTreeHostCommon;
 class LayerTreeImpl;
+class LayerTreeSettings;
 class PriorityCalculator;
 class RenderingStatsInstrumentation;
 class ResourceUpdateQueue;
 class ScrollbarLayerInterface;
 class SimpleEnclosedRegion;
 struct AnimationEvent;
 template <typename LayerType>
 class OcclusionTracker;
 
 // Base class for composited layers. Special layer types are derived from
@@ skipping 331 matching lines @@
                                       float* contents_scale_x,
                                       float* contents_scale_y,
                                       gfx::Size* content_bounds);
 
   LayerTreeHost* layer_tree_host() { return layer_tree_host_; }
   const LayerTreeHost* layer_tree_host() const { return layer_tree_host_; }
 
   // Set the priority of all desired textures in this layer.
   virtual void SetTexturePriorities(const PriorityCalculator& priority_calc) {}
 
+  static void SetCompositorAnimationTimelinesEnabled(bool enabled);
+
   bool AddAnimation(scoped_ptr<Animation> animation);
   void PauseAnimation(int animation_id, double time_offset);
   void RemoveAnimation(int animation_id);
   void RemoveAnimation(int animation_id, Animation::TargetProperty property);
 
   LayerAnimationController* layer_animation_controller() {
     return layer_animation_controller_.get();
   }
   void SetLayerAnimationControllerForTest(
       scoped_refptr<LayerAnimationController> controller);
 
   void set_layer_animation_delegate(AnimationDelegate* delegate) {
+    DCHECK(layer_animation_controller_);

[danakj, 2015/05/08 18:21:40]

i don't think this DCHECK is doing much for you? you'd just null-deref on the
next line anyways.

[loyso (OOO), 2015/05/11 06:59:43]

It makes the problem clear. null-deref is undefined behavior.

     layer_animation_controller_->set_layer_animation_delegate(delegate);
   }
 
   bool HasActiveAnimation() const;
+  void RegisterForAnimations(AnimationRegistrar* registrar,
+                             const LayerTreeSettings& settings);
 
   void AddLayerAnimationEventObserver(
       LayerAnimationEventObserver* animation_observer);
   void RemoveLayerAnimationEventObserver(
       LayerAnimationEventObserver* animation_observer);
 
   virtual SimpleEnclosedRegion VisibleContentOpaqueRegion() const;
 
   virtual ScrollbarLayerInterface* ToScrollbarLayer();
 
@@ skipping 313 matching lines @@
 
   std::vector<FrameTimingRequest> frame_timing_requests_;
   bool frame_timing_requests_dirty_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_H_