Verify that contentsTextureManager is non-NULL before dereferencing it.

cc/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 "config.h"
 
 #include "cc/thread_proxy.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/delay_based_time_source.h"
@@ skipping 353 matching lines @@
     // The texture upload queue may reference textures that were just purged, clear
     // them from the queue.
     if (m_currentResourceUpdateControllerOnImplThread.get())
         m_currentResourceUpdateControllerOnImplThread->discardUploadsToEvictedResources();
     return true;
 }
 
 void ThreadProxy::sendManagedMemoryStats()
 {
     DCHECK(isImplThread());
-    if (m_layerTreeHostImpl.get() && m_layerTreeHostImpl->renderer())
-        m_layerTreeHostImpl->renderer()->sendManagedMemoryStats(
-            m_layerTreeHost->contentsTextureManager()->memoryVisibleBytes(),
-            m_layerTreeHost->contentsTextureManager()->memoryVisibleAndNearbyBytes(),
-            m_layerTreeHost->contentsTextureManager()->memoryUseBytes());
+    if (!m_layerTreeHostImpl.get())
+        return;
+    if (!m_layerTreeHostImpl->renderer())
+        return;
+    if (!m_layerTreeHost->contentsTextureManager())
+        return;
+
+    m_layerTreeHostImpl->renderer()->sendManagedMemoryStats(
+        m_layerTreeHost->contentsTextureManager()->memoryVisibleBytes(),
+        m_layerTreeHost->contentsTextureManager()->memoryVisibleAndNearbyBytes(),
+        m_layerTreeHost->contentsTextureManager()->memoryUseBytes());
 }
 
 void ThreadProxy::setNeedsRedraw()
 {
     DCHECK(isMainThread());
     TRACE_EVENT0("cc", "ThreadProxy::setNeedsRedraw");
     Proxy::implThread()->postTask(createThreadTask(this, &ThreadProxy::setFullRootLayerDamageOnImplThread));
     Proxy::implThread()->postTask(createThreadTask(this, &ThreadProxy::setNeedsRedrawOnImplThread));
 }
 
@@ skipping 584 matching lines @@
 ThreadProxy::BeginFrameAndCommitState::BeginFrameAndCommitState()
     : monotonicFrameBeginTime(0)
 {
 }
 
 ThreadProxy::BeginFrameAndCommitState::~BeginFrameAndCommitState()
 {
 }
 
 }  // namespace cc