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).

CHROMIUM_BUILD_COMPATIBILITY.txt

@@ -7,5 +7,5 @@
 # https://bitbucket.org/chromiumembedded/cef/wiki/BranchesAndBuilding
 
 {
-  'chromium_checkout': 'cb947c0153db0ec02a8abbcb3ca086d88bf6006f',
+  'chromium_checkout': '304f01a1e1f7ebeb7d637f847469c90ba008b86d',
 }