Remove gfx::FrameTime for a single clock source

ui/compositor/layer_animator.cc

Index: ui/compositor/layer_animator.cc
diff --git a/ui/compositor/layer_animator.cc b/ui/compositor/layer_animator.cc
index 7bc870300c17efe02b096a9e5f0e45f62dc56b13..1d4f333bdbdcf065c3be2286c591ede45d9c3ff2 100644
--- a/ui/compositor/layer_animator.cc
+++ b/ui/compositor/layer_animator.cc
@@ -15,7 +15,6 @@
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/layer_animation_sequence.h"
 #include "ui/compositor/layer_animator_collection.h"
-#include "ui/gfx/frame_time.h"
 
 #define SAFE_INVOKE_VOID(function, running_anim, ...) \
     if (running_anim.is_sequence_alive()) \
@@ -182,7 +181,7 @@ void LayerAnimator::StartTogether(
     if (collection && collection->HasActiveAnimators())
       last_step_time_ = collection->last_tick_time();
     else
-      last_step_time_ = gfx::FrameTime::Now();
+      last_step_time_ = base::TimeTicks::Now();
   }
 
   // Collect all the affected properties.
@@ -770,7 +769,7 @@ bool LayerAnimator::StartSequenceImmediately(LayerAnimationSequence* sequence) {
   else if (collection && collection->HasActiveAnimators())
     start_time = collection->last_tick_time();
   else
-    start_time = gfx::FrameTime::Now();
+    start_time = base::TimeTicks::Now();
 
   if (!sequence->animation_group_id())
     sequence->set_animation_group_id(cc::AnimationIdProvider::NextGroupId());