Revert "Add popup client support for injected scroll gestures."

This reverts commit 287cb74411764899a208aed78aca940bfd75ce9b.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Add popup client support for injected scroll gestures.
> 
> I missed adding support for injecting scroll gestures to
> PagePopupChromeClient and scrollbar presses broke for select popups
> that had scrollbars. Add an override that forwards to the
> WebWidgetClient and add a test that validates that this works correctly.
> 
> R=​bokan@chromium.org
> 
> Bug: 960747
> Change-Id: I7a5164bb3d8c7b15252d0a9a806e932f7cc269a9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600444
> Reviewed-by: David Bokan <bokan@chromium.org>
> Commit-Queue: Daniel Libby <dlibby@microsoft.com>
> Cr-Commit-Position: refs/heads/master@{#658137}

TBR=bokan@chromium.org,dlibby@microsoft.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 960747
Change-Id: Ib4ee6e5ef03910ef9b6253e03381cd1dcc780431
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613756
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Daniel Libby <dlibby@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#660661}
2 files changed