Add explicit base namespace to string16 users.

chrome/common/spellcheck_result.h

 // 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.
 
 #ifndef CHROME_COMMON_SPELLCHECK_RESULT_H_
 #define CHROME_COMMON_SPELLCHECK_RESULT_H_
 
 #include "base/strings/string16.h"
 
 // This class mirrors blink::WebTextCheckingResult which holds a
@@ skipping 10 matching lines @@
 
     // No underline for words that spellcheck needs to track. For example, a
     // word in the custom spellcheck dictionary.
     INVISIBLE = 1 << 3,
   };
 
   explicit SpellCheckResult(
       Decoration d = SPELLING,
       int loc = 0,
       int len = 0,
-      const string16& rep = string16(),
+      const base::string16& rep = base::string16(),
       uint32 h = 0)
       : decoration(d), location(loc), length(len), replacement(rep), hash(h) {
   }
 
   Decoration decoration;
   int location;
   int length;
-  string16 replacement;
+  base::string16 replacement;
   uint32 hash;
 };
 
 #endif  // CHROME_COMMON_SPELLCHECK_RESULT_H_