[Cocoa] Make TabContentsContainerView more testable for interactive_ui_tests.

ui/base/test/ui_controls_mac.mm

 // Copyright 2013 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.
 
 #include "ui/base/test/ui_controls.h"
 
 #import <Cocoa/Cocoa.h>
 #include <mach/mach_time.h>
 #include <vector>
 
@@ skipping 371 matching lines @@
 bool SendMouseClick(MouseButton type) {
   CHECK(g_ui_controls_enabled);
   return SendMouseEventsNotifyWhenDone(type, UP|DOWN, base::Closure());
 }
 
 void RunClosureAfterAllPendingUIEvents(const base::Closure& closure) {
   base::MessageLoop::current()->PostTask(
       FROM_HERE, base::Bind(&EventQueueWatcher, closure));
 }
 
+bool IsFullKeyboardAccessEnabled() {
+  return [NSApp isFullKeyboardAccessEnabled];
+}
+
 }  // namespace ui_controls