Force Taskbar to remain stashed when in 3p launcher or recents

This patch makes it so that the transient Taskbar cannot unstash when in 3P launcher.

Previously, the user was able to unstash Taskbar when in 3P launcher, causing a janky-looking UI (3P launchers may implement their own version of Taskbar on the home screen. This also caused problems with certain Taskbar commands like split screen, which provide an entry portal to Pixel-specific implementations.

Fixed by forcing the Taskbar to stay stashed when a 3P Launcher is displayed. The Taskbar is still usable inside of other non-launcher apps. This was done by using TopTaskTracker to check for ACTIVITY_TYPE_HOME or ACTIVITY_TYPE_RECENTS, and disabling Taskbar when these activities are running.

Fixes: 277963491
Test: Manual
Change-Id: Ifc0f3c07e3b76eb610f93205978fbc596bab6253
7 files changed