Add base:: to straggling string16 in content/.

content/shell/renderer/test_runner/MockSpellCheck.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 MockSpellCheck_h
 #define MockSpellCheck_h
 
 #include <vector>
 
 #include "third_party/WebKit/public/platform/WebNonCopyable.h"
@@ skipping 38 matching lines @@
     // Initialize the internal resources if we need to initialize it.
     // Initializing this object may take long time. To prevent from hurting
     // the performance of test_shell, we initialize this object when
     // SpellCheckWord() is called for the first time.
     // To be compliant with SpellCheck:InitializeIfNeeded(), this function
     // returns true if this object is downloading a dictionary, otherwise
     // it returns false.
     bool initializeIfNeeded();
 
     // A table that consists of misspelled words.
-    std::vector<string16> m_misspelledWords;
+    std::vector<base::string16> m_misspelledWords;
 
     // A flag representing whether or not this object is initialized.
     bool m_initialized;
 };
 
 }
 
 #endif // MockSpellCheck_h