Add base:: to string16s in chrome/.

chrome/test/chromedriver/key_converter.h

Index: chrome/test/chromedriver/key_converter.h
diff --git a/chrome/test/chromedriver/key_converter.h b/chrome/test/chromedriver/key_converter.h
index 4cbb0b4c2b80e509217b91761a588ae85f5f39f9..eabc6caec384c03032c4a5b95dbd5ae4f5396314 100644
--- a/chrome/test/chromedriver/key_converter.h
+++ b/chrome/test/chromedriver/key_converter.h
@@ -26,7 +26,7 @@ KeyEvent CreateCharEvent(const std::string& unmodified_text,
 // an error message. If |release_modifiers| is true, all modifiers would be
 // depressed. |modifiers| acts both an input and an output, however, only when
 // the conversion process is successful will |modifiers| be changed.
-Status ConvertKeysToKeyEvents(const string16& keys,
+Status ConvertKeysToKeyEvents(const base::string16& keys,
                               bool release_modifiers,
                               int* modifiers,
                               std::list<KeyEvent>* key_events);