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/chrome_browser_process_stub.h

@@ -31,7 +31,8 @@ class ChromeBrowserProcessStub : public BrowserProcess {
   // BrowserProcess implementation.
   void ResourceDispatcherHostCreated() override;
   void EndSession() override;
-  MetricsServicesManager* GetMetricsServicesManager() override;
+  metrics_services_manager::MetricsServicesManager*
+      GetMetricsServicesManager() override;
   metrics::MetricsService* metrics_service() override;
   rappor::RapporService* rappor_service() override;
   IOThread* io_thread() override;