InjectCssCallback

This callback is invoked when the document element has been created and a custom style sheet can be injected into the document.

Return the inject response to inject a custom stylesheet into the document.

Return the proceed response to continue loading without injecting a custom style sheet into the document.

If the callback throws an exception, the InjectCssResponseCallback.proceed() method will be invoked.

This callback may be invoked several times for the same frame.

Important: the engine will be blocked until you return control from the callback.