[Mac] Fix fullscreen tabstrip animation

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

Index: chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.mm
diff --git a/chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.mm b/chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.mm
index 3a59bf24e05959e5522dbd97712094b9c3d765f8..9f56cd16516b55bf47a894835ea302277766d17b 100644
--- a/chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.mm
+++ b/chrome/browser/ui/cocoa/fullscreen/fullscreen_toolbar_animation_controller.mm
@@ -54,17 +54,19 @@ void FullscreenToolbarAnimationController::AnimateToolbarForTabstripChanges() {
   if ([owner_ mustShowFullscreenToolbar])
     return;
 
-  AnimateToolbarIn();
+  if (animation_.IsShowing()) {
+    hide_toolbar_timer_.Reset();
+    return;
+  }
+
   should_hide_toolbar_after_delay_ = true;
+  AnimateToolbarIn();
 }
 
 void FullscreenToolbarAnimationController::AnimateToolbarIn() {
   if (![owner_ isInFullscreen])
     return;
 
-  if (animation_.IsShowing())
-    return;
-
   animation_.Reset(animation_start_value_);
   animation_.Show();
 }