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).

tests/unittests/test_handler.h

@@ -317,6 +317,7 @@ void WaitForThread(CefRefPtr<CefTaskRunner> task_runner);
 
 #define WaitForIOThread() WaitForThread(TID_IO)
 #define WaitForUIThread() WaitForThread(TID_UI)
+#define WaitForDBThread() WaitForThread(TID_DB)
 
 // Returns true if the currently running test has failed.
 bool TestFailed();