cc: Add layer-based pixel tests.

cc/test/layer_tree_test_common.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/test/layer_tree_test_common.h"
 
 #include "cc/animation.h"
 #include "cc/animation_registrar.h"
 #include "cc/content_layer.h"
 #include "cc/input_handler.h"
@@ skipping 80 matching lines @@
         result = false;
     return result;
 }
 
 void MockLayerTreeHostImpl::DrawLayers(FrameData* frame)
 {
     LayerTreeHostImpl::DrawLayers(frame);
     m_testHooks->drawLayersOnThread(this);
 }
 
+bool MockLayerTreeHostImpl::SwapBuffers()
+{
+    bool result = LayerTreeHostImpl::SwapBuffers();
+    m_testHooks->swapBuffersOnThread(this, result);
+    return result;
+}
+
 bool MockLayerTreeHostImpl::ActivatePendingTreeIfNeeded()
 {
     if (!pending_tree())
         return false;
 
     if (!m_testHooks->canActivatePendingTree())
         return false;
 
     bool activated = LayerTreeHostImpl::ActivatePendingTreeIfNeeded();
     if (activated)
@@ skipping 403 matching lines @@
     ASSERT_FALSE(m_layerTreeHost.get());
     m_client.reset();
     if (m_timedOut) {
         FAIL() << "Test timed out";
         return;
     }
     afterTest();
 }
 
 }  // namespace cc