[Mac RTL] Draw the drop arrow in the correct location when mirrored.

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 2188 matching lines @@
             givesIndex:&index
            disposition:&disposition
            activateTab:YES];
 
   NSPoint arrowPos = NSMakePoint(0, arrowBaseY);
   if (index == -1) {
     // Append a tab at the end.
     DCHECK(disposition == WindowOpenDisposition::NEW_FOREGROUND_TAB);
     NSInteger lastIndex = [tabArray_ count] - 1;
     NSRect overRect = [[[tabArray_ objectAtIndex:lastIndex] view] frame];
-    arrowPos.x = overRect.origin.x + overRect.size.width - kTabOverlap / 2.0;
+    if (cocoa_l10n_util::ShouldDoExperimentalRTLLayout()) {
+      arrowPos.x = NSMinX(overRect) + kTabOverlap / 2.0;
+    } else {
+      arrowPos.x = NSMaxX(overRect) - kTabOverlap / 2.0;
+    }
   } else {
     NSRect overRect = [[[tabArray_ objectAtIndex:index] view] frame];
     switch (disposition) {
       case WindowOpenDisposition::NEW_FOREGROUND_TAB:
-        // Insert tab (to the left of the given tab).
-        arrowPos.x = overRect.origin.x + kTabOverlap / 2.0;
+        // Insert tab (before the given tab).
+        if (cocoa_l10n_util::ShouldDoExperimentalRTLLayout()) {
+          arrowPos.x = NSMaxX(overRect) - kTabOverlap / 2.0;
+        } else {
+          arrowPos.x = NSMinX(overRect) + kTabOverlap / 2.0;
+        }
         break;
       case WindowOpenDisposition::CURRENT_TAB:
         // Overwrite the given tab.
         arrowPos.x = overRect.origin.x + overRect.size.width / 2.0;
         break;
       default:
         NOTREACHED();
     }
   }
 
@@ skipping 183 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