Revert of cc: Adding BeginFrameTracker object and removing Now() from LTHI.

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 9a37e2f5d0c6bb967c9667899a6794dd6d7ce3ff..c09a2abdd0fd3ee6c6335f55c55559935a6caf40 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -33,7 +33,6 @@
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/tile_manager.h"
 #include "cc/resources/ui_resource_client.h"
-#include "cc/scheduler/begin_frame_tracker.h"
 #include "cc/scheduler/commit_earlyout_reason.h"
 #include "cc/scheduler/draw_result.h"
 #include "cc/scheduler/video_frame_controller.h"
@@ -447,12 +446,12 @@
   void SetTreePriority(TreePriority priority);
   TreePriority GetTreePriority() const;
 
-  // TODO(mithro): Remove this methods which exposes the internal
-  // BeginFrameArgs to external callers.
   virtual BeginFrameArgs CurrentBeginFrameArgs() const;
 
   // Expected time between two begin impl frame calls.
-  base::TimeDelta CurrentBeginFrameInterval() const;
+  base::TimeDelta begin_impl_frame_interval() const {
+    return begin_impl_frame_interval_;
+  }
 
   void AsValueWithFrameInto(FrameData* frame,
                             base::trace_event::TracedValue* value) const;
@@ -561,8 +560,6 @@
 
   LayerTreeHostImplClient* client_;
   Proxy* proxy_;
-
-  BeginFrameTracker current_begin_frame_tracker_;
 
  private:
   gfx::Vector2dF ScrollLayerWithViewportSpaceDelta(
@@ -735,6 +732,11 @@
 
   gfx::Rect viewport_damage_rect_;
 
+  BeginFrameArgs current_begin_frame_args_;
+
+  // Expected time between two begin impl frame calls.
+  base::TimeDelta begin_impl_frame_interval_;
+
   scoped_ptr<AnimationRegistrar> animation_registrar_;
   std::set<ScrollbarAnimationController*> scrollbar_animation_controllers_;
   std::set<VideoFrameController*> video_frame_controllers_;