Revert "Implement scroll handler latency tracking"

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index f5142f925e413404df06c65b195e438a4373a812..d6dd2c5e903974a5f38a2f65f751802239361eee 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -317,8 +317,6 @@ class CC_EXPORT LayerTreeHostImpl
   bool scroll_affects_scroll_handler() const {
     return scroll_affects_scroll_handler_;
   }
-  void QueueSwapPromiseForMainThreadScrollUpdate(
-      scoped_ptr<SwapPromise> swap_promise);
 
   bool IsCurrentlyScrolling() const;
 
@@ -552,9 +550,6 @@ class CC_EXPORT LayerTreeHostImpl
   void MarkUIResourceNotEvicted(UIResourceId uid);
 
   void NotifySwapPromiseMonitorsOfSetNeedsRedraw();
-  void NotifySwapPromiseMonitorsOfForwardingToMainThread();
-  void BreakSwapPromisesForMainThreadScrollUpdate(
-      SwapPromise::DidNotSwapReason reason);
 
   typedef base::hash_map<UIResourceId, UIResourceData>
       UIResourceMap;
@@ -601,7 +596,6 @@ class CC_EXPORT LayerTreeHostImpl
   bool wheel_scrolling_;
   bool scroll_affects_scroll_handler_;
   int scroll_layer_id_when_mouse_over_scrollbar_;
-  ScopedPtrVector<SwapPromise> swap_promises_for_main_thread_scroll_update_;
 
   bool tile_priorities_dirty_;