GitLab

This is to allow associating cast apps with platform views.
WebviewService will be deprecated in future change.

Bug: b/136460199
Test: Compile cast_shell
Change-Id: I5bad0fe7817ec65e3719d9c43d0b08fcb679cd80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1856278Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Commit-Queue: Shawn Gallea <sagallea@google.com>
Cr-Commit-Position: refs/heads/master@{#705216}