Add base:: to string16s in win8/.

win8/metro_driver/ime/text_service_delegate.h

 // 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.
 
 #ifndef WIN8_METRO_DRIVER_IME_TEXT_SERVICE_DELEGATE_H_
 #define WIN8_METRO_DRIVER_IME_TEXT_SERVICE_DELEGATE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/strings/string16.h"
 
 namespace metro_viewer {
 struct UnderlineInfo;
 }
 
 namespace metro_driver {
 
 // A delegate which works together with virtual text service.
 // Objects that implement this delegate will receive notifications from a
 // virtual text service whenever an IME updates the composition or commits text.
 class TextServiceDelegate {
  public:
   virtual ~TextServiceDelegate() {}
 
   // Called when on-going composition is updated. An empty |text| represents
   // that the composition is canceled.
   virtual void OnCompositionChanged(
-      const string16& text,
+      const base::string16& text,
       int32 selection_start,
       int32 selection_end,
       const std::vector<metro_viewer::UnderlineInfo>& underlines) = 0;
 
   // Called when |text| is committed.
-  virtual void OnTextCommitted(const string16& text) = 0;
+  virtual void OnTextCommitted(const base::string16& text) = 0;
 };
 
 }  // namespace metro_driver
 
 #endif  // WIN8_METRO_DRIVER_IME_TEXT_SERVICE_DELEGATE_H_