Add base:: to string16 in Source/testing/runner/.

Source/testing/runner/MockSpellCheck.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 63 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