Update some uses of char16 to use the base:: namespace.

chrome/test/chromedriver/keycode_text_conversion_mac.mm

 // Copyright (c) 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.
 
 #include "chrome/test/chromedriver/keycode_text_conversion.h"
 
 #import <Carbon/Carbon.h>
 
 #include <cctype>
 
@@ skipping 56 matching lines @@
     base::string16 text16;
     text16.push_back(character);
     *text = base::UTF16ToUTF8(text16);
     return true;
   }
   *text = std::string();
   return true;
 }
 
 bool ConvertCharToKeyCode(
-    char16 key, ui::KeyboardCode* key_code, int *necessary_modifiers,
+    base::char16 key, ui::KeyboardCode* key_code, int *necessary_modifiers,
     std::string* error_msg) {
   base::string16 key_string;
   key_string.push_back(key);
   std::string key_string_utf8 = base::UTF16ToUTF8(key_string);
   bool found_code = false;
   *error_msg = std::string();
   // There doesn't seem to be a way to get a mac key code for a given unicode
   // character. So here we check every key code to see if it produces the
   // right character. We could cache the results and regenerate everytime the
   // language changes, but this brute force technique has negligble performance
@@ skipping 15 matching lines @@
       *necessary_modifiers = kShiftKeyModifierMask;
       found_code = true;
     }
     if (found_code) {
       *key_code = code;
       break;
     }
   }
   return found_code;
 }