GitLab

While not fully moving the InstallHelpers to a component yet, this
reduces their dependency on //chrome specific code, and gets them a step
closer to being moved to //components. The main dependencies that needed
to be broken were on Tab/TabUtils. Tab was typically used to get the
WebContents and the Activity. WebContents are now passed directly
in, rather than gotten from the Tab (which in C++ code was gotten from
the WebContents anyway...), and are then used to get the top level
window and thus the appropriate corresponding activity.

In addition to removing these dependencies on TabUtils, the ArCore's
install helper *also* now uses ApplicationStatus to track when it is
resumed, thus reducing it's dependency on ChromeActivity. This is
similar to what Vr does for it's DFM install. VR's install path is a bit
different in that it launches an activity for a result, and thus that is
not changed quite yet.

Bug: 960542
Change-Id: Ia42a73ecd1c491ee9899f8113a2905860b66366a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2438639
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Auto-Submit: Alexander Cooper <alcooper@chromium.org>
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Reviewed-by: Piotr Bialecki <bialpio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813350}