Currently Blink has unit tests for WebViewImpl (third_party/WebKit/Source/web/tests/WebViewTest.cpp), which cover a lot of widget functionality for top-level frames, but there are no equivalent tests for WebFrameWidgets that cover equivalent behavior on out-of-process iframes.

An example is that there should be a test for setting a GPU rasterization trigger, which was noted missing in  bug 712794 .

I'm assigning this to myself but don't plan to do it immediately, so no objection if it is stolen by somebody who has a bit of time.