GitLab

This is needed for CastContentWindow to receive
backgesture support notifications

Merge-With: eureka-internal/367600
Bug: Internal b/149740737
Test: Build cast_shell
Change-Id: Iacde9b0687106b1093572fa0b2f8339a2d7b5bf1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2071015Reviewed-by: Sean Topping <seantopping@chromium.org>
Reviewed-by: Ryan Daum <rdaum@chromium.org>
Commit-Queue: Shawn Gallea <sagallea@google.com>
Cr-Commit-Position: refs/heads/master@{#744791}