gfx: Add FrameTime and DisplayTime classes

cc/input/top_controls_manager.cc

Index: cc/input/top_controls_manager.cc
diff --git a/cc/input/top_controls_manager.cc b/cc/input/top_controls_manager.cc
index a0e61aaa325b49a83021825cf17d78626c5b332a..1220a0071193e43eb60c6111bb64726904b9a888 100644
--- a/cc/input/top_controls_manager.cc
+++ b/cc/input/top_controls_manager.cc
@@ -136,11 +136,11 @@ void TopControlsManager::SetControlsTopOffset(float controls_top_offset) {
   client_->DidChangeTopControlsPosition();
 }
 
-gfx::Vector2dF TopControlsManager::Animate(base::TimeTicks monotonic_time) {
+gfx::Vector2dF TopControlsManager::Animate(gfx::FrameTime monotonic_time) {
   if (!top_controls_animation_ || !client_->HaveRootScrollLayer())
     return gfx::Vector2dF();
 
-  double time = (monotonic_time - base::TimeTicks()).InMillisecondsF();
+  double time = monotonic_time.Unsafe_InMillisecondsF();
 
   float old_offset = controls_top_offset_;
   SetControlsTopOffset(top_controls_animation_->GetValue(time));
@@ -175,7 +175,7 @@ void TopControlsManager::SetupAnimation(AnimationDirection direction) {
 
   top_controls_animation_ = KeyframedFloatAnimationCurve::Create();
   double start_time =
-      (gfx::FrameTime::Now() - base::TimeTicks()).InMillisecondsF();
+      gfx::FrameTime::Now().Unsafe_InMillisecondsF();
   top_controls_animation_->AddKeyframe(
       FloatKeyframe::Create(start_time, controls_top_offset_,
                             scoped_ptr<TimingFunction>()));
@@ -213,11 +213,12 @@ void TopControlsManager::StartAnimationIfNecessary() {
   }
 }
 
-bool TopControlsManager::IsAnimationCompleteAtTime(base::TimeTicks time) {
+bool TopControlsManager::IsAnimationCompleteAtTime(
+    gfx::FrameTime time) {
   if (!top_controls_animation_)
     return true;
 
-  double time_ms = (time - base::TimeTicks()).InMillisecondsF();
+  double time_ms = time.Unsafe_InMillisecondsF();
   float new_offset = top_controls_animation_->GetValue(time_ms);
 
   if ((animation_direction_ == SHOWING_CONTROLS && new_offset >= 0) ||