[DevTools] Fix frontend host race and assert.

content/renderer/devtools/devtools_client.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 "content/renderer/devtools/devtools_client.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/common/devtools_messages.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/renderer/render_view_impl.h"
 #include "third_party/WebKit/public/platform/WebFloatPoint.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/web/WebDevToolsFrontend.h"
 #include "ui/base/ui_base_switches.h"
 
 using blink::WebDevToolsFrontend;
 using blink::WebString;
 
 namespace content {
 
 DevToolsClient::DevToolsClient(
     RenderFrame* main_render_frame,
     const std::string& compatibility_script)
     : RenderFrameObserver(main_render_frame),
-      compatibility_script_(compatibility_script) {
-  const base::CommandLine& command_line =
-      *base::CommandLine::ForCurrentProcess();
-  web_tools_frontend_.reset(WebDevToolsFrontend::create(
-      main_render_frame->GetRenderView()->GetWebView(), this,
-      base::ASCIIToUTF16(command_line.GetSwitchValueASCII(switches::kLang))));
+      compatibility_script_(compatibility_script),
+      web_tools_frontend_(
+          WebDevToolsFrontend::create(main_render_frame->GetWebFrame(), this)) {
 }
 
 DevToolsClient::~DevToolsClient() {
 }
 
 void DevToolsClient::DidClearWindowObject() {
   if (!compatibility_script_.empty())
     render_frame()->ExecuteJavaScript(base::UTF8ToUTF16(compatibility_script_));
 }
 
 void DevToolsClient::sendMessageToEmbedder(const WebString& message) {
   Send(new DevToolsHostMsg_DispatchOnEmbedder(routing_id(),
                                               message.utf8()));
 }
 
 bool DevToolsClient::isUnderTest() {
   return RenderThreadImpl::current()->layout_test_mode();
 }
 
 }  // namespace content