Avoid exposing cc::Layer tree to CompositorProxy

third_party/WebKit/Source/web/CompositorMutatorImpl.h

 // Copyright 2016 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 CompositorMutatorImpl_h
 #define CompositorMutatorImpl_h
 
 #include <memory>
 #include "core/animation/CustomCompositorAnimationManager.h"
 #include "platform/graphics/CompositorMutator.h"
 #include "platform/heap/Handle.h"
 #include "platform/heap/HeapAllocator.h"
 #include "platform/wtf/Noncopyable.h"
 
 namespace blink {
 
 class CompositorAnimator;
 class CompositorMutatorClient;
+class CompositorProxy;
 
 // Fans out requests from the compositor to all of the registered
 // CompositorAnimators which can then mutate layers through their respective
 // mutate interface. Requests for animation frames are received from
 // CompositorAnimators and sent to the compositor to generate a new compositor
 // frame.
 //
 // Owned by the control thread (unless threaded compositing is disabled).
 // Should be accessed only on the compositor thread.
 class CompositorMutatorImpl final : public CompositorMutator {
   WTF_MAKE_NONCOPYABLE(CompositorMutatorImpl);
 
  public:
   static std::unique_ptr<CompositorMutatorClient> CreateClient();
   static CompositorMutatorImpl* Create();
 
   // CompositorMutator implementation.
   bool Mutate(double monotonic_time_now,
               CompositorMutableStateProvider*) override;
 
   void RegisterCompositorAnimator(CompositorAnimator*);
   void UnregisterCompositorAnimator(CompositorAnimator*);
 
+  void RegisterCompositorProxy(const CompositorProxy*);
+  void UnregisterCompositorProxy(const CompositorProxy*);
+
   void SetNeedsMutate();
 
   void SetClient(CompositorMutatorClient* client) { client_ = client; }
   CustomCompositorAnimationManager* AnimationManager() {
     return animation_manager_.get();
   }
 
  private:
   CompositorMutatorImpl();
 
   using CompositorAnimators =
       HashSet<CrossThreadPersistent<CompositorAnimator>>;
   CompositorAnimators animators_;
 
   std::unique_ptr<CustomCompositorAnimationManager> animation_manager_;
   CompositorMutatorClient* client_;
 };
 
 }  // namespace blink
 
 #endif  // CompositorMutatorImpl_h