Use a lock to deal with concurrent access to the m_evictedBackings

cc/tiled_layer_unittest.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/tiled_layer.h"
 
 #include "cc/bitmap_content_layer_updater.h"
 #include "cc/layer_painter.h"
 #include "cc/overdraw_metrics.h"
 #include "cc/rendering_stats.h"
@@ skipping 76 matching lines @@
         }
         FakeTiledLayerImpl* operator->()
         {
             return m_layerImpl;
         }
     private:
         FakeTiledLayerImpl* m_layerImpl;
     };
     void resourceManagerClearAllMemory(PrioritizedResourceManager* resourceManager, ResourceProvider* resourceProvider)
     {
-        DebugScopedSetImplThreadAndMainThreadBlocked implThreadAndMainThreadBlocked(m_proxy);
-        resourceManager->clearAllMemory(resourceProvider);
-        resourceManager->reduceMemory(resourceProvider);
+        {
+            DebugScopedSetImplThreadAndMainThreadBlocked implThreadAndMainThreadBlocked(m_proxy);
+            resourceManager->clearAllMemory(resourceProvider);
+            resourceManager->reduceMemory(resourceProvider);
+        }
+        resourceManager->unlinkAndClearEvictedBackings();
     }
     void updateTextures()
     {
         DebugScopedSetImplThreadAndMainThreadBlocked implThreadAndMainThreadBlocked(m_proxy);
         DCHECK(m_queue);
         scoped_ptr<ResourceUpdateController> updateController =
             ResourceUpdateController::create(
                 NULL,
                 m_proxy->implThread(),
                 m_queue.Pass(),
@@ skipping 1509 matching lines @@
 
     // Invalidate the entire layer in layer space. When painting, the rect given to webkit should match the layer's bounds.
     layer->setNeedsDisplayRect(layerRect);
     layer->update(*m_queue.get(), 0, m_stats);
 
     EXPECT_RECT_EQ(layerRect, layer->trackingLayerPainter()->paintedRect());
 }
 
 }  // namespace
 }  // namespace cc