Remove redundant PageMsg_UpdateWindowScreenRect IPC path.

This path sends the window screen rect, through the RenderViewImpl
of the main frame, to the RenderWidget. But it does so immediately
after sending the window screen rect + widget screen rect to the
same RenderWidget.

There is an exception which is when an InterstitialPageImpl is present
in the WebContents. Then we would have sent the window screen rect to
that interstitial's main frame (via its RenderViewImpl). Instead,
walk the full frame tree of the InterstitialPageImpl (don't assume only
one widget) and go through the RenderWidgetHostImpl to send both
rects using the same code path as we would for a non-interstitial.

Then we remove the PageMsg_UpdateWindowScreenRect IPC and all of the
plumbing around it.

R=nasko@chromium.org

Bug: 912193
Change-Id: I6f2d21f40e548d3eb4d8104cea9427a5118a0f2b
Reviewed-on: https://chromium-review.googlesource.com/c/1448631
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629291}
9 files changed