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/browser_context_impl.h

@@ -68,6 +68,7 @@ class CefBrowserContextImpl : public CefBrowserContext {
   content::PushMessagingService* GetPushMessagingService() override;
   content::SSLHostStateDelegate* GetSSLHostStateDelegate() override;
   content::PermissionManager* GetPermissionManager() override;
+  content::BackgroundSyncController* GetBackgroundSyncController() override;
 
   // Profile methods.
   PrefService* GetPrefs() override;