Prepare CompositorWorker for per thread heap

third_party/WebKit/Source/web/CompositorMutatorImpl.cpp

 // 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.
 
 #include "web/CompositorMutatorImpl.h"
 
 #include "core/animation/CustomCompositorAnimationManager.h"
 #include "core/dom/CompositorProxy.h"
 #include "platform/CrossThreadFunctional.h"
 #include "platform/TraceEvent.h"
@@ skipping 57 matching lines @@
         if (client->mutate(monotonicTimeNow, stateProvider))
             needToReinvoke = true;
     }
 
     return needToReinvoke;
 }
 
 void CompositorMutatorImpl::registerProxyClient(CompositorProxyClientImpl* client)
 {
     TRACE_EVENT0("compositor-worker", "CompositorMutatorImpl::registerClient");
+    DCHECK(!m_proxyClients.contains(client));
     m_proxyClients.add(client);
     setNeedsMutate();
 }
 
+void CompositorMutatorImpl::unregisterProxyClient(CompositorProxyClientImpl* client)
+{
+    DCHECK(m_proxyClients.contains(client));
+    m_proxyClients.remove(client);
+}
+
 void CompositorMutatorImpl::setNeedsMutate()
 {
     TRACE_EVENT0("compositor-worker", "CompositorMutatorImpl::setNeedsMutate");
     m_client->setNeedsMutate();
 }
 
 } // namespace blink