Move CrTrackingArea from chrome/browser/ui/cocoa to ui/base/cocoa.

ui/base/cocoa/tracking_area.mm

 // Copyright (c) 2011 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/tracking_area.h"
+#import "ui/base/cocoa/tracking_area.h"
 
 #include "base/logging.h"
 
 // NSTrackingArea does not retain its |owner| so CrTrackingArea wraps the real
 // owner in this proxy, which can stop forwarding messages to the owner when
 // it is no longer |alive_|.
 @interface CrTrackingAreaOwnerProxy : NSObject {
  @private
   // Whether or not the owner is "alive" and should forward calls to the real
   // owner object.
@@ skipping 86 matching lines @@
 }
 
 - (void)windowWillClose:(NSNotification*)notif {
   [self clearOwner];
 }
 
 @end
 
 // Scoper //////////////////////////////////////////////////////////////////////
 
+namespace ui {
+
 ScopedCrTrackingArea::ScopedCrTrackingArea(CrTrackingArea* tracking_area)
     : tracking_area_(tracking_area) {
 }
 
 ScopedCrTrackingArea::~ScopedCrTrackingArea() {
   [tracking_area_ clearOwner];
 }
 
 void ScopedCrTrackingArea::reset(CrTrackingArea* tracking_area) {
   tracking_area_.reset(tracking_area);
 }
 
 CrTrackingArea* ScopedCrTrackingArea::get() const {
   return tracking_area_.get();
 }
+
+}  // namespace ui