Use a lock to deal with concurrent access to the m_evictedBackings

cc/single_thread_proxy.cc

 // Copyright 2011 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 "cc/single_thread_proxy.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/draw_quad.h"
 #include "cc/graphics_context.h"
 #include "cc/layer_tree_host.h"
@@ skipping 324 matching lines @@
     NOTREACHED();
 }
 
 bool SingleThreadProxy::commitAndComposite()
 {
     DCHECK(Proxy::isMainThread());
 
     if (!m_layerTreeHost->initializeRendererIfNeeded())
         return false;
 
-    // Unlink any texture backings that were deleted
-    PrioritizedResourceManager::BackingList evictedContentsTexturesBackings;
-    {
-        DebugScopedSetImplThread impl(this);
-        m_layerTreeHost->contentsTextureManager()->getEvictedBackings(evictedContentsTexturesBackings);
-    }
-    m_layerTreeHost->contentsTextureManager()->unlinkEvictedBackings(evictedContentsTexturesBackings);
+    m_layerTreeHost->contentsTextureManager()->unlinkAndClearEvictedBackings();
 
     scoped_ptr<ResourceUpdateQueue> queue = make_scoped_ptr(new ResourceUpdateQueue);
     m_layerTreeHost->updateLayers(*(queue.get()), m_layerTreeHostImpl->memoryAllocationLimitBytes());
 
     if (m_layerTreeHostImpl->contentsTexturesPurged())
         m_layerTreeHostImpl->resetContentsTexturesPurged();
 
     m_layerTreeHost->willCommit();
     doCommit(queue.Pass());
     bool result = doComposite();
@@ skipping 38 matching lines @@
 
 void SingleThreadProxy::didSwapFrame()
 {
     if (m_nextFrameIsNewlyCommittedFrame) {
         m_nextFrameIsNewlyCommittedFrame = false;
         m_layerTreeHost->didCommitAndDrawFrame();
     }
 }
 
 }  // namespace cc