cc: Plumbing for impl thread micro benchmarks

cc/debug/micro_benchmark.h

Index: cc/debug/micro_benchmark.h
diff --git a/cc/debug/micro_benchmark.h b/cc/debug/micro_benchmark.h
index 92c9b7501573973fcc4c2fa4d02e72676b12e80a..9ad2b67c40dd58ee92927921818c95cbfa47ec5c 100644
--- a/cc/debug/micro_benchmark.h
+++ b/cc/debug/micro_benchmark.h
@@ -10,6 +10,7 @@
 
 namespace base {
 class Value;
+class MessageLoopProxy;
 }  // namespace base
 
 namespace cc {
@@ -17,6 +18,7 @@ namespace cc {
 class LayerTreeHost;
 class Layer;
 class PictureLayer;
+class MicroBenchmarkImpl;
 class MicroBenchmark {
  public:
   typedef base::Callback<void(scoped_ptr<base::Value>)> DoneCallback;
@@ -30,6 +32,9 @@ class MicroBenchmark {
   virtual void RunOnLayer(Layer* layer);
   virtual void RunOnLayer(PictureLayer* layer);
 
+  virtual scoped_ptr<MicroBenchmarkImpl> CreateBenchmarkImpl(
+      scoped_refptr<base::MessageLoopProxy> origin_loop);
+
  protected:
   void NotifyDone(scoped_ptr<base::Value> result);