cc: Removing base::TimeTicks argument to DrawLayers as it isn't used.

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index c254311a9300edb65bc8d9006bb6e5c613c6f6f1..8174b5502eafae2ccfad677d11a5d99eb7e548b2 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -429,7 +429,7 @@ bool SingleThreadProxy::DoComposite(
 
     if (!layer_tree_host_impl_->IsContextLost()) {
       layer_tree_host_impl_->PrepareToDraw(frame);
-      layer_tree_host_impl_->DrawLayers(frame, frame_begin_time);

[danakj, 2014/07/02 18:51:38]

How does the frame_begin_time get to the LTHI for DrawLayers in this case? Would
this break the FPS counter in the UI compositor? --ui-show-fps-counter to see
it. If not, can you explain why not?

[mithro-old, 2014/07/07 05:27:32]

(I fixed this code to use the CurrentFrameTimeTicks() method.)

The internal current_time_ticks_ value is updated in the above Animate call if
it hasn't already been set.

BTW Would it make more sense that the fps_counter_ is updated in Animate? It is
the only thing which talks about time in this area, everything else is about
doing the actual drawing.

[danakj, 2014/07/07 20:56:44]

The problem with doing it in animate is that we don't necessarily draw after
animate, and we want the fps meter to track only frames that we draw.

There are many ways to shave this yak, like we could save the time in the
FrameData instead or something.

So this frame_begin_time is unused in the impl-side of a single-thread
draw/composite. Can we stop passing it?

+      layer_tree_host_impl_->DrawLayers(frame);
       layer_tree_host_impl_->DidDrawAllLayers(*frame);
     }
     lost_output_surface = layer_tree_host_impl_->IsContextLost();