[ refactor ] Remove RenderView::GetWebFrameWidget

This API is only used in AndroidWebview which gets it from the RenderView of
a RenderFrame. It makes more sense to get a WebFrameWidget from the
(local root) WebLocalFrame that owns it.

Bug: none
Change-Id: I3f62359893ec7b06dc5512045aa4e16426304dde
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1596830
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Ehsan Karamad <ekaramad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#656899}
5 files changed