Use explicit WebString conversions in LayoutTest related files

components/test_runner/mock_spell_check.cc

 // Copyright 2014 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 "components/test_runner/mock_spell_check.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 30 matching lines @@
 
   // Initialize this spellchecker.
   InitializeIfNeeded();
 
   // Reset the result values as our spellchecker does.
   *misspelled_offset = 0;
   *misspelled_length = 0;
 
   // Convert to a base::string16 because we store base::string16 instances in
   // misspelled_words_ and blink::WebString has no find().
-  base::string16 string_text = text;
+  base::string16 string_text = text.utf16();
   int skipped_length = 0;
 
   while (!string_text.empty()) {
     // Extract the first possible English word from the given string.
     // The given string may include non-ASCII characters or numbers. So, we
     // should filter out such characters before start looking up our
     // misspelled-word table.
     // (This is a simple version of our SpellCheckWordIterator class.)
     // If the given string doesn't include any ASCII characters, we can treat
     // the string as valid one.
@@ skipping 107 matching lines @@
   // Mark as initialized to prevent this object from being initialized twice
   // or more.
   initialized_ = true;
 
   // Since this MockSpellCheck class doesn't download dictionaries, this
   // function always returns false.
   return false;
 }
 
 }  // namespace test_runner