Rename Animate as Begin(Main)Frame

Rename Animate as Begin(Main)Frame to harmonize the terminology used by
different parts of the system. The monotonic start time of the last frame
that is passed into this function is also renamed for consistency.

No functional changes.

Original patch by Simon Pick ([email protected]).

BUG=346230

Review URL: https://codereview.chromium.org/429743003

Cr-Commit-Position: refs/heads/master@{#290248}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290248 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 759b80ef..f442ca2 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -744,8 +744,8 @@
   return layer_tree_host_impl_->pinch_gesture_active();
 }
 
-base::TimeTicks LayerTreeImpl::CurrentFrameTimeTicks() const {
-  return layer_tree_host_impl_->CurrentFrameTimeTicks();
+BeginFrameArgs LayerTreeImpl::CurrentBeginFrameArgs() const {
+  return layer_tree_host_impl_->CurrentBeginFrameArgs();
 }
 
 base::TimeDelta LayerTreeImpl::begin_impl_frame_interval() const {