[exp] cc: Introduce cc::CompositorMutator.

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 1379d0893468e459fc11b0494b84ae98f15394e0..e73c31c41e64b7c1539b055b114d0c45cbd2394c 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -49,6 +49,7 @@ class GpuMemoryBufferManager;
 namespace cc {
 class AnimationRegistrar;
 class BeginFrameSource;
+class CompositorMutator;
 class HeadsUpDisplayLayer;
 class Layer;
 class LayerTreeHostImpl;
@@ -75,6 +76,7 @@ class CC_EXPORT LayerTreeHost {
       LayerTreeHostClient* client,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+      CompositorMutator* compositor_mutator,
       const LayerTreeSettings& settings,
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
@@ -85,6 +87,7 @@ class CC_EXPORT LayerTreeHost {
       LayerTreeHostSingleThreadClient* single_thread_client,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+      CompositorMutator* compositor_mutator,
       const LayerTreeSettings& settings,
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       scoped_ptr<BeginFrameSource> external_begin_frame_source);
@@ -307,6 +310,7 @@ class CC_EXPORT LayerTreeHost {
   LayerTreeHost(LayerTreeHostClient* client,
                 SharedBitmapManager* shared_bitmap_manager,
                 gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+                CompositorMutator* compositor_mutator,
                 const LayerTreeSettings& settings);
   void InitializeThreaded(
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
@@ -441,6 +445,8 @@ class CC_EXPORT LayerTreeHost {
   SharedBitmapManager* shared_bitmap_manager_;
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
 
+  CompositorMutator* compositor_mutator_;

[loyso (OOO), 2015/04/13 08:03:21]

JUST NOTE: This is exactly what I have here:
https://codereview.chromium.org/947033002/patch/160001/170021

1) AnimationHost is aggregated in LayerTreeHost/LayerTreeHostImpl
2) AnimationHost will eventually be decoupled via LayerTreemutators
(CompositorMutator?) abstract interface.

+
   ScopedPtrVector<SwapPromise> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;