Don't expose a LayerImpl reference to CompositorProxy.

third_party/WebKit/Source/web/CompositorWorkerProxyClientImpl.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 "web/CompositorWorkerProxyClientImpl.h"
 
 #include "core/dom/CompositorProxy.h"
 #include "modules/compositorworker/CompositorWorkerGlobalScope.h"
 #include "platform/graphics/CompositorMutableStateProvider.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
 #include "web/CompositorMutatorImpl.h"
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
 // A helper class that updates proxies mutable state on creation and reset it
 // on destruction. This can be used with rAF callback to ensure no mutation is
 // allowed outside rAF.
 class ScopedCompositorMutableState final {
   WTF_MAKE_NONCOPYABLE(ScopedCompositorMutableState);
   STACK_ALLOCATED();
 
  public:
   ScopedCompositorMutableState(
       HeapHashSet<WeakMember<CompositorProxy>>& proxies,
       CompositorMutableStateProvider* stateProvider)
       : m_proxies(proxies) {
     for (CompositorProxy* proxy : m_proxies) {
       proxy->takeCompositorMutableState(
-          stateProvider->getMutableStateFor(proxy->elementId()));
+          stateProvider->getMutableStateFor(proxy->proxyId()));
     }
   }
   ~ScopedCompositorMutableState() {
     for (CompositorProxy* proxy : m_proxies)
       proxy->takeCompositorMutableState(nullptr);
   }
 
  private:
   HeapHashSet<WeakMember<CompositorProxy>>& m_proxies;
 };
@@ skipping 64 matching lines @@
   DCHECK(m_globalScope);
   // Convert to zero based document time in milliseconds consistent with
   // requestAnimationFrame.
   double highResTimeMs =
       1000.0 * (monotonicTimeNow - m_globalScope->timeOrigin());
   return m_globalScope->executeAnimationFrameCallbacks(highResTimeMs);
 }
 
 void CompositorWorkerProxyClientImpl::registerCompositorProxy(
     CompositorProxy* proxy) {
+  TRACE_EVENT0("compositor-worker",
+               "CompositorWorkerProxyClientImpl::registerCompositorProxy");
+  m_mutator->registerCompositorProxy(proxy);
   m_proxies.insert(proxy);
 }
 
 void CompositorWorkerProxyClientImpl::unregisterCompositorProxy(
     CompositorProxy* proxy) {
+  TRACE_EVENT0("compositor-worker",
+               "CompositorWorkerProxyClientImpl::unregisterCompositorProxy");
+  m_mutator->registerCompositorProxy(proxy);
   m_proxies.erase(proxy);
 }
 
 }  // namespace blink