cc: Add a blocksPendingCommit flag to LayerImpl

cc/texture_layer.cc

 // Copyright 2010 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/texture_layer.h"
 
 #include "cc/layer_tree_host.h"
 #include "cc/texture_layer_client.h"
 #include "cc/texture_layer_impl.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebGraphicsContext3D.h"
@@ skipping 113 matching lines @@
     Layer::pushPropertiesTo(layer);
 
     TextureLayerImpl* textureLayer = static_cast<TextureLayerImpl*>(layer);
     textureLayer->setFlipped(m_flipped);
     textureLayer->setUVRect(m_uvRect);
     textureLayer->setPremultipliedAlpha(m_premultipliedAlpha);
     textureLayer->setTextureId(m_textureId);
     m_contentCommitted = drawsContent();
 }
 
+bool TextureLayer::blocksPendingCommit() const
+{
+    // Double-buffered texture layers need to be blocked until they can be made
+    // triple-buffered.  Single-buffered layers already prevent draws, so
+    // can block too for simplicity.
+    return true;
+}
+
 }  // namespace cc