Don't expose a LayerImpl reference to CompositorProxy.

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

 // 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.
 
 #include "core/dom/CompositorProxy.h"
 
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/dom/CompositorWorkerProxyClient.h"
 #include "core/dom/DOMNodeIds.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/workers/WorkerClients.h"
 #include "core/workers/WorkerGlobalScope.h"
 #include "platform/CrossThreadFunctional.h"
 #include "platform/graphics/CompositorMutableProperties.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebTraceLocation.h"
 #include <algorithm>
 
 namespace blink {
+namespace {
+uint64_t uniqueId = 0;
+}  // namespace
 
 static const struct {
   const char* name;
   uint32_t property;
 } allowedProperties[] = {
     {"opacity", CompositorMutableProperty::kOpacity},
     {"scrollleft", CompositorMutableProperty::kScrollLeft},
     {"scrolltop", CompositorMutableProperty::kScrollTop},
     {"transform", CompositorMutableProperty::kTransform},
 };
@@ skipping 96 matching lines @@
         CompositorWorkerProxyClient::from(clients);
     return new CompositorProxy(elementId, compositorMutableProperties, client);
   }
 
   return new CompositorProxy(elementId, compositorMutableProperties);
 }
 
 CompositorProxy::CompositorProxy(uint64_t elementId,
                                  uint32_t compositorMutableProperties)
     : m_elementId(elementId),
+      m_proxyId(uniqueId++),
       m_compositorMutableProperties(compositorMutableProperties),
       m_client(nullptr) {
   DCHECK(m_compositorMutableProperties);
 #if DCHECK_IS_ON()
   DCHECK(sanityCheckMutableProperties(m_compositorMutableProperties));
 #endif
 
   if (isMainThread()) {
     incrementCompositorProxiedPropertiesForElement(
         m_elementId, m_compositorMutableProperties);
@@ skipping 151 matching lines @@
         m_elementId, m_compositorMutableProperties);
   } else {
     Platform::current()->mainThread()->getWebTaskRunner()->postTask(
         BLINK_FROM_HERE,
         crossThreadBind(&decrementCompositorProxiedPropertiesForElement,
                         m_elementId, m_compositorMutableProperties));
   }
 }
 
 }  // namespace blink