Update to Chromium revision 304f01a1 (#358063)

- Improve ordering of CefLoadHandler callbacks. OnLoadingStateChange will
  be called before and after all calls to OnLoadStart and OnLoadEnd.
  OnLoadStart/OnLoadEnd calls will occur as matching pairs
  (see http://crbug.com/539952#c2).
- Remove the |requesting_url| argument to CefGeolocationHandler::
  OnCancelGeolocationPermission. Clients can use the |request_id| argument
  to track this information themselves.
- Fix a crash when loading the PDF extension in multiple browsers with a
  custom CefRequestContext (issue #1757).

libcef/browser/component_updater/cef_component_updater_configurator.cc

@@ -126,8 +126,6 @@ class CefConfigurator : public Configurator {
   bool UseBackgroundDownloader() const override;
   scoped_refptr<base::SequencedTaskRunner> GetSequencedTaskRunner()
       const override;
-  scoped_refptr<base::SingleThreadTaskRunner> GetSingleThreadTaskRunner()
-      const override;
 
  private:
   friend class base::RefCountedThreadSafe<CefConfigurator>;
@@ -289,12 +287,6 @@ CefConfigurator::GetSequencedTaskRunner() const {
           base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
 }
 
-scoped_refptr<base::SingleThreadTaskRunner>
-CefConfigurator::GetSingleThreadTaskRunner() const {
-  return content::BrowserThread::GetMessageLoopProxyForThread(
-      content::BrowserThread::FILE);
-}
-
 }  // namespace
 
 scoped_refptr<update_client::Configurator>