Convert string16 to base::string16 in content.

content/browser/web_contents/web_contents_view_mac.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 <Carbon/Carbon.h>
 
 #import "content/browser/web_contents/web_contents_view_mac.h"
 
 #include <string>
 
@@ skipping 314 matching lines @@
   // going on.
   [cocoa_view_.get() setNextKeyView:view_view];
   return view;
 }
 
 RenderWidgetHostView* WebContentsViewMac::CreateViewForPopupWidget(
     RenderWidgetHost* render_widget_host) {
   return RenderWidgetHostViewPort::CreateViewForWidget(render_widget_host);
 }
 
-void WebContentsViewMac::SetPageTitle(const string16& title) {
+void WebContentsViewMac::SetPageTitle(const base::string16& title) {
   // Meaningless on the Mac; widgets don't have a "title" attribute
 }
 
 
 void WebContentsViewMac::RenderViewCreated(RenderViewHost* host) {
   // We want updates whenever the intrinsic width of the webpage changes.
   // Put the RenderView into that mode. The preferred width is used for example
   // when the "zoom" button in the browser window is clicked.
   host->EnablePreferredSizeMode();
 }
@@ skipping 221 matching lines @@
       [[[notification userInfo] objectForKey:kSelectionDirection]
         unsignedIntegerValue];
   if (direction == NSDirectSelection)
     return;
 
   [self webContents]->
       FocusThroughTabTraversal(direction == NSSelectingPrevious);
 }
 
 @end