Implement the behavior after receiving auto translation request.

Send the TranslationRequest which collected from the UI toolkit to
the TranslationService. And apply the result to the UI toolkit to
show the translated text.

Bug: 172969740
Bug: 177887860
Test: Verified by using a sample app and made sure the full flow work
and the text was replaced with translated text.

Change-Id: I1db4d1eabe5bc65d8785f13f760af54f74e46c97