Remove unneeded ScopedLayerAnimationSettings::LockTransitionDuration()

ui/compositor/scoped_layer_animation_settings.h

Index: ui/compositor/scoped_layer_animation_settings.h
diff --git a/ui/compositor/scoped_layer_animation_settings.h b/ui/compositor/scoped_layer_animation_settings.h
index e8a1b468ba6f94df2fb1baf1dbfd93704756c40b..e36b853272990789e6b0def70c52ea54c8529126 100644
--- a/ui/compositor/scoped_layer_animation_settings.h
+++ b/ui/compositor/scoped_layer_animation_settings.h
@@ -34,12 +34,6 @@ class COMPOSITOR_EXPORT ScopedLayerAnimationSettings {
   void SetTransitionDuration(base::TimeDelta duration);
   base::TimeDelta GetTransitionDuration() const;
 
-  // Locks transition duration in |animator_|. When transition duration
-  // is locked any subsequent changes to it are ignored until the
-  // ScopedLayerAnimationSettings object that has locked the duration goes out
-  // of scope.
-  void LockTransitionDuration();
-
   void SetTweenType(gfx::Tween::Type tween_type);
   gfx::Tween::Type GetTweenType() const;
 
@@ -56,7 +50,6 @@ class COMPOSITOR_EXPORT ScopedLayerAnimationSettings {
 
  private:
   LayerAnimator* animator_;
-  bool old_is_transition_duration_locked_;
   base::TimeDelta old_transition_duration_;
   gfx::Tween::Type old_tween_type_;
   LayerAnimator::PreemptionStrategy old_preemption_strategy_;