[Mac] Fix fullscreen tabstrip animation

chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.h"
 
 #import "chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_controller.h"
 
 namespace {
 
@@ skipping 36 matching lines @@
 void FullscreenToolbarAnimationController::StopAnimationAndTimer() {
   animation_.Stop();
   hide_toolbar_timer_.Stop();
 }
 
 void FullscreenToolbarAnimationController::AnimateToolbarForTabstripChanges() {
   // Don't kickstart the animation if the toolbar is already displayed.
   if ([owner_ mustShowFullscreenToolbar])
     return;
 
+  if (animation_.IsShowing()) {
+    hide_toolbar_timer_.Reset();
+    return;
+  }
+
+  should_hide_toolbar_after_delay_ = true;
   AnimateToolbarIn();
-  should_hide_toolbar_after_delay_ = true;
 }
 
 void FullscreenToolbarAnimationController::AnimateToolbarIn() {
   if (![owner_ isInFullscreen])
     return;
 
-  if (animation_.IsShowing())
-    return;
-
   animation_.Reset(animation_start_value_);
   animation_.Show();
 }
 
 void FullscreenToolbarAnimationController::AnimateToolbarOutIfPossible() {
   if (![owner_ isInFullscreen] || [owner_ mustShowFullscreenToolbar])
     return;
 
   if (animation_.IsClosing())
     return;
@@ skipping 24 matching lines @@
   [owner_ updateToolbarLayout];
 }
 
 void FullscreenToolbarAnimationController::AnimationEnded(
     const gfx::Animation* animation) {
   if (animation_.IsShowing() && should_hide_toolbar_after_delay_) {
     hide_toolbar_timer_.Reset();
     should_hide_toolbar_after_delay_ = false;
   }
 }