[DevTools] Fix frontend host race and assert.

chrome/browser/devtools/devtools_ui_bindings.h

 // 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.
 
 #ifndef CHROME_BROWSER_DEVTOOLS_DEVTOOLS_UI_BINDINGS_H_
 #define CHROME_BROWSER_DEVTOOLS_DEVTOOLS_UI_BINDINGS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 201 matching lines @@
   scoped_ptr<DevToolsFileHelper> file_helper_;
   scoped_refptr<DevToolsFileSystemIndexer> file_system_indexer_;
   typedef std::map<
       int,
       scoped_refptr<DevToolsFileSystemIndexer::FileSystemIndexingJob> >
       IndexingJobsMap;
   IndexingJobsMap indexing_jobs_;
 
   bool devices_updates_enabled_;
   bool frontend_loaded_;
+  bool frontend_reattaching_;
   scoped_ptr<DevToolsTargetsUIHandler> remote_targets_handler_;
   scoped_ptr<PortForwardingStatusSerializer> port_status_serializer_;
   PrefChangeRegistrar pref_change_registrar_;
   scoped_ptr<DevToolsEmbedderMessageDispatcher> embedder_message_dispatcher_;
   GURL url_;
   using PendingRequestsMap = std::map<const net::URLFetcher*, DispatchCallback>;
   PendingRequestsMap pending_requests_;
   base::WeakPtrFactory<DevToolsUIBindings> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsUIBindings);
 };
 
 #endif  // CHROME_BROWSER_DEVTOOLS_DEVTOOLS_UI_BINDINGS_H_