Implement scroll handler latency tracking

cc/trees/layer_tree_host_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/trees/layer_tree_host.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/synchronization/lock.h"
@@ skipping 4512 matching lines @@
   virtual ~SimpleSwapPromiseMonitor() {}
 
   virtual void OnSetNeedsCommitOnMain() OVERRIDE {
     (*set_needs_commit_count_)++;
   }
 
   virtual void OnSetNeedsRedrawOnImpl() OVERRIDE {
     (*set_needs_redraw_count_)++;
   }
 
+  virtual void OnForwardScrollUpdateToMainThreadOnImpl() OVERRIDE {
+    ADD_FAILURE() << "Should not get called on main thread.";
+  }
+
  private:
   int* set_needs_commit_count_;
   int* set_needs_redraw_count_;
 };
 
 class LayerTreeHostTestSimpleSwapPromiseMonitor : public LayerTreeHostTest {
  public:
   virtual void BeginTest() OVERRIDE { PostSetNeedsCommitToMainThread(); }
 
   virtual void WillBeginMainFrame() OVERRIDE {
@@ skipping 351 matching lines @@
   const gfx::Size bounds_;
   FakeContentLayerClient client_;
   scoped_refptr<ContentLayerWithUpdateTracking> content_layer_;
   scoped_refptr<FakePictureLayer> picture_layer_;
   Layer* child_layer_;
 };
 
 MULTI_THREAD_TEST_F(LayerTreeHostTestContinuousPainting);
 
 }  // namespace cc