Start/stop WebKitThread from BrowserMainLoop like other BrowserThreads.

content/browser/renderer_host/resource_dispatcher_host.h

Index: content/browser/renderer_host/resource_dispatcher_host.h
diff --git a/content/browser/renderer_host/resource_dispatcher_host.h b/content/browser/renderer_host/resource_dispatcher_host.h
index 38cd1eb932758577cb03c238e998624e17de7d77..21be2a34aebd608af89b3f88ed9c768e4819874b 100644
--- a/content/browser/renderer_host/resource_dispatcher_host.h
+++ b/content/browser/renderer_host/resource_dispatcher_host.h
@@ -38,7 +38,6 @@ class ResourceHandler;
 class ResourceMessageFilter;
 class SaveFileManager;
 class TabContents;
-class WebKitThread;
 struct DownloadSaveInfo;
 struct GlobalRequestID;
 struct ResourceHostMsg_Request;
@@ -151,10 +150,6 @@ class CONTENT_EXPORT ResourceDispatcherHost : public net::URLRequest::Delegate {
     return save_file_manager_;
   }
 
-  WebKitThread* webkit_thread() const {
-    return webkit_thread_.get();
-  }
-
   // Called when the unload handler for a cross-site request has finished.
   void OnSwapOutACK(const ViewMsg_SwapOut_Params& params);
 
@@ -457,9 +452,6 @@ class CONTENT_EXPORT ResourceDispatcherHost : public net::URLRequest::Delegate {
   // We own the save file manager.
   scoped_refptr<SaveFileManager> save_file_manager_;
 
-  // We own the WebKit thread and see to its destruction.
-  scoped_ptr<WebKitThread> webkit_thread_;
-
   // Request ID for browser initiated requests. request_ids generated by
   // child processes are counted up from 0, while browser created requests
   // start at -2 and go down from there. (We need to start at -2 because -1 is