Convert string16 to base::string16 in content.

content/browser/accessibility/accessibility_tree_formatter_mac.mm

 // Copyright (c) 2012 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 "content/browser/accessibility/accessibility_tree_formatter.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
@@ skipping 143 matching lines @@
     } else if (value != nil) {
       dict->SetString(
           SysNSStringToUTF8(requestedAttribute),
           SysNSStringToUTF16([NSString stringWithFormat:@"%@", value]));
     }
   }
   dict->Set(kPositionDictAttr, PopulatePosition(node).release());
   dict->Set(kSizeDictAttr, PopulateSize(cocoa_node).release());
 }
 
-string16 AccessibilityTreeFormatter::ToString(const base::DictionaryValue& dict,
-                                              const string16& indent) {
-  string16 line;
+base::string16 AccessibilityTreeFormatter::ToString(
+    const base::DictionaryValue& dict,
+    const base::string16& indent) {
+  base::string16 line;
   NSArray* defaultAttributes =
       [NSArray arrayWithObjects:NSAccessibilityTitleAttribute,
                                 NSAccessibilityValueAttribute,
                                 nil];
   string s_value;
   dict.GetString(SysNSStringToUTF8(NSAccessibilityRoleAttribute), &s_value);
   WriteAttribute(true, UTF8ToUTF16(s_value), &line);
 
   string subroleAttribute = SysNSStringToUTF8(NSAccessibilitySubroleAttribute);
   if (dict.GetString(subroleAttribute, &s_value)) {
@@ skipping 64 matching lines @@
 const string AccessibilityTreeFormatter::GetAllowString() {
   return "@MAC-ALLOW:";
 }
 
 // static
 const string AccessibilityTreeFormatter::GetDenyString() {
   return "@MAC-DENY:";
 }
 
 }  // namespace content