Remove usage of deprecated V8 APIs from c/r/extensions

chrome/renderer/extensions/document_custom_bindings.cc

 // Copyright 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/renderer/extensions/document_custom_bindings.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "chrome/renderer/extensions/chrome_v8_context.h"
@@ skipping 12 matching lines @@
 }
 
 // Attach an event name to an object.
 void DocumentCustomBindings::RegisterElement(
     const v8::FunctionCallbackInfo<v8::Value>& args) {
   if (args.Length() != 2 || !args[0]->IsString() || !args[1]->IsObject()) {
     NOTREACHED();
     return;
   }
 
-  std::string element_name(*v8::String::AsciiValue(args[0]));
+  std::string element_name(*v8::String::Utf8Value(args[0]));
   v8::Local<v8::Object> options = args[1]->ToObject();
 
   blink::WebExceptionCode ec = 0;
   blink::WebDocument document = context()->web_frame()->document();
   v8::Handle<v8::Value> constructor =
       document.registerEmbedderCustomElement(
           blink::WebString::fromUTF8(element_name), options, ec);
   args.GetReturnValue().Set(constructor);
 }
 
 }  // namespace extensions