Verify that contentsTextureManager is non-NULL before dereferencing it.

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 "config.h"
 
 #include "cc/single_thread_proxy.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/draw_quad.h"
@@ skipping 271 matching lines @@
     DCHECK(isImplThread());
     if (!m_layerTreeHost->contentsTextureManager())
         return false;
 
     return m_layerTreeHost->contentsTextureManager()->reduceMemoryOnImplThread(limitBytes, priorityCutoff, m_layerTreeHostImpl->resourceProvider());
 }
 
 void SingleThreadProxy::sendManagedMemoryStats()
 {
     DCHECK(Proxy::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());
 }
 
 // Called by the legacy scheduling path (e.g. where render_widget does the scheduling)
 void SingleThreadProxy::compositeImmediately()
 {
     if (commitAndComposite()) {
         m_layerTreeHostImpl->swapBuffers();
         didSwapFrame();
     }
 }
@@ skipping 76 matching lines @@
 
 void SingleThreadProxy::didSwapFrame()
 {
     if (m_nextFrameIsNewlyCommittedFrame) {
         m_nextFrameIsNewlyCommittedFrame = false;
         m_layerTreeHost->didCommitAndDrawFrame();
     }
 }
 
 }