gfx: Add FrameTime and DisplayTime classes

cc/layers/heads_up_display_layer_impl.cc

Index: cc/layers/heads_up_display_layer_impl.cc
diff --git a/cc/layers/heads_up_display_layer_impl.cc b/cc/layers/heads_up_display_layer_impl.cc
index b7437bff1c9bc5384b7cbd11accb5e1d31e313ee..750e79ca01e0c55f7909fb5b13a7c8fc1eb8615e 100644
--- a/cc/layers/heads_up_display_layer_impl.cc
+++ b/cc/layers/heads_up_display_layer_impl.cc
@@ -188,9 +188,9 @@ void HeadsUpDisplayLayerImpl::UpdateHudContents() {
   const LayerTreeDebugState& debug_state = layer_tree_impl()->debug_state();
 
   // Don't update numbers every frame so text is readable.
-  base::TimeTicks now = layer_tree_impl()->CurrentFrameTimeTicks();
-  if (base::TimeDelta(now - time_of_last_graph_update_).InSecondsF() > 0.25f) {
-    time_of_last_graph_update_ = now;
+  gfx::FrameTime frame_time = layer_tree_impl()->CurrentFrameTimeTicks();
+  if ((frame_time - time_of_last_graph_update_).InSecondsF() > 0.25f) {
+    time_of_last_graph_update_ = frame_time;
 
     if (debug_state.show_fps_counter) {
       FrameRateCounter* fps_counter = layer_tree_impl()->frame_rate_counter();