Rewrite base::JSONReader to be 35-40% faster, depending on the input string.

chrome/browser/ui/webui/tab_modal_confirm_dialog_webui.cc

 // 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 "chrome/browser/ui/webui/tab_modal_confirm_dialog_webui.h"
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 81 matching lines @@
   ChromeWebUIDataSource::SetFontAndTextDirection(&dict);
   std::string json;
   base::JSONWriter::Write(&dict, &json);
   return json;
 }
 
 void TabModalConfirmDialogWebUI::OnDialogClosed(
     const std::string& json_retval) {
   bool accepted = false;
   if (!json_retval.empty()) {
-    base::JSONReader reader;
-    scoped_ptr<Value> value(reader.JsonToValue(json_retval, false, false));
+    scoped_ptr<Value> value(base::JSONReader::Read(json_retval));
     if (!value.get() || !value->GetAsBoolean(&accepted))
       NOTREACHED() << "Missing or unreadable response from dialog";
   }
 
   delegate_->set_window(NULL);
   if (accepted)
     delegate_->Accept();
   else
     delegate_->Cancel();
   delete this;
 }
 
 void TabModalConfirmDialogWebUI::OnCloseContents(WebContents* source,
                                                  bool* out_close_dialog) {}
 
 bool TabModalConfirmDialogWebUI::ShouldShowDialogTitle() const {
   return true;
 }