GitLab

In anticipation of the RenderWidget removal, move RequestPresentation
into WebWidgetTestProxy and rename it to match the bindings name.

BUG=1097816

Change-Id: I1fa060ee6d3c788bb519830ae61a0e01bebcb859
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2499741
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821459}