[Mac] Make new tab button animation RTL-aware

chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm

 // Copyright (c) 2012 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/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 1162 matching lines @@
     if (!NSEqualRects(newTabTargetFrame_, newTabNewFrame)) {
       // Set the new tab button image correctly based on where the cursor is.
       NSWindow* window = [tabStripView_ window];
       NSPoint currentMouse = [window mouseLocationOutsideOfEventStream];
       currentMouse = [tabStripView_ convertPoint:currentMouse fromView:nil];
 
       BOOL shouldShowHover = [newTabButton_ pointIsOverButton:currentMouse];
       [self setNewTabButtonHoverState:shouldShowHover];
 
       // Move the new tab button into place. We want to animate the new tab
-      // button if it's moving to the left (closing a tab), but not when it's
-      // moving to the right (inserting a new tab). If moving right, we need
+      // button if it's moving back (closing a tab), but not when it's
+      // moving forward (inserting a new tab). If moving forward, we need
       // to use a very small duration to make sure we cancel any in-flight
       // animation to the left.
       if (visible && animate) {
         ScopedNSAnimationContextGroup localAnimationGroup(true);
-        BOOL movingLeft = NSMinX(newTabNewFrame) < NSMinX(newTabTargetFrame_);
-        if (!movingLeft) {
+        BOOL movingBack = NSMinX(newTabNewFrame) < NSMinX(newTabTargetFrame_);
+        if (cocoa_l10n_util::ShouldDoExperimentalRTLLayout())
+          movingBack = !movingBack;
+
+        if (!movingBack) {
           localAnimationGroup.SetCurrentContextShortestDuration();
         }
         [[newTabButton_ animator] setFrame:newTabNewFrame];
         newTabTargetFrame_ = newTabNewFrame;
       } else {
         [newTabButton_ setFrame:newTabNewFrame];
         newTabTargetFrame_ = newTabNewFrame;
       }
     }
   }
@@ skipping 1134 matching lines @@
   for (int i = 0; i < tabStripModel_->count(); i++) {
     [self updateIconsForContents:tabStripModel_->GetWebContentsAt(i) atIndex:i];
   }
 }
 
 - (void)setVisualEffectsDisabledForFullscreen:(BOOL)fullscreen {
   [tabStripView_ setVisualEffectsDisabledForFullscreen:fullscreen];
 }
 
 @end