Avoid exposing cc::Layer tree to CompositorProxy

third_party/WebKit/Source/core/dom/CompositorProxy.h

 // Copyright 2015 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 CompositorProxy_h
 #define CompositorProxy_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
 #include "core/dom/CompositorProxyClient.h"
@@ skipping 21 matching lines @@
                                  const Vector<String>& attribute_array,
                                  ExceptionState&);
   static CompositorProxy* Create(ExecutionContext*,
                                  uint64_t element,
                                  uint32_t compositor_mutable_properties);
   virtual ~CompositorProxy();
 
   DECLARE_TRACE();
 
   uint64_t ElementId() const { return element_id_; }
+  uint64_t ProxyId() const { return proxy_id_; }
   uint32_t CompositorMutableProperties() const {
     return compositor_mutable_properties_;
   }
   bool supports(const String& attribute) const;
 
   bool initialized() const { return connected_ && state_.get(); }
   bool Connected() const { return connected_; }
   void disconnect();
 
   double opacity(ExceptionState&) const;
@@ skipping 13 matching lines @@
   CompositorProxy(Element&, const Vector<String>& attribute_array);
   CompositorProxy(uint64_t element,
                   uint32_t compositor_mutable_properties,
                   CompositorProxyClient*);
 
  private:
   bool RaiseExceptionIfNotMutable(uint32_t compositor_mutable_property,
                                   ExceptionState&) const;
   void DisconnectInternal();
 
+  const uint64_t proxy_id_ = 0;
   const uint64_t element_id_ = 0;
   const uint32_t compositor_mutable_properties_ = 0;
 
   bool connected_ = true;
   Member<CompositorProxyClient> client_;
   std::unique_ptr<CompositorMutableState> state_;
 };
 
 }  // namespace blink
 
 #endif  // CompositorProxy_h