Update some uses of UTF conversions in chrome/browser to use the base:: namespace.

chrome/browser/spellchecker/word_trimmer.h

 // Copyright (c) 2011 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_BROWSER_SPELLCHECKER_WORD_TRIMMER_H_
 #define CHROME_BROWSER_SPELLCHECKER_WORD_TRIMMER_H_
 
 #include "base/strings/string16.h"
 
 // Trims |text| to contain only the range from |start| to |end| and |keep| words
 // on either side of the range. The |start| and |end| parameters are character
 // indexes into |text|. The |keep| parameter is the number of words to keep on
 // either side of the |start|-|end| range. The function updates |start| in
 // accordance with the trimming.
 //
 // Example:
 //
 //  size_t start = 14;
 //  size_t end = 23;
 //  base::string16 text =
-//      ASCIIToUTF16("one two three four five six seven eight");
+//      base::ASCIIToUTF16("one two three four five six seven eight");
 //  int keep = 2;
 //  base::string16 trimmed = TrimWords(&start, end, text, keep);
-//  DCHECK(trimmed == ASCIIToUTF16("two three four five six seven"));
+//  DCHECK(trimmed == base::ASCIIToUTF16("two three four five six seven"));
 //  DCHECK(start == 10);
 //
 base::string16 TrimWords(size_t* start,
                          size_t end,
                          const base::string16& text,
                          size_t keep);
 
 #endif  // CHROME_BROWSER_SPELLCHECKER_WORD_TRIMMER_H_