cocoa: add experimental tabstrip keyboard focus support

chrome/browser/ui/cocoa/tabs/tab_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_controller.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/i18n/rtl.h"
@@ skipping 472 matching lines @@
     return [[self target] performSelector:@selector(inRapidClosureMode)] ?
         YES : NO;
   }
   return NO;
 }
 
 - (void)maybeStartDrag:(NSEvent*)event forTab:(TabController*)tab {
   [[target_ dragController] maybeStartDrag:event forTab:tab];
 }
 
+- (void)keyUp:(NSEvent*)event {
+  unichar keyChar = [[event characters] characterAtIndex:0];
+  if (keyChar == '\r' || keyChar == '\n')
+    [self selectTab:self];
+}
+
 @end