Able to enter MockHomeActivity in picture in picture.

[colinrtwhite]

Hi! Thanks for creating this example for managing the task backstack while using PiP.

I noticed that it's possible to force MockHomeActivity into picture in picture even though supportsPictureInPicture isn't enabled for it in the manifest. To reproduce:

• Open WatchActivity in PiP.
• Kill MockHomeActivity/MockDetailsActivity using the multi task menu.
• Tap on the app's launcher icon.

Result: MockHomeActivity will be launched into picture in picture mode.

Expected behaviour: Either MockHomeActivity is launched in a new task not in PiP or WatchActivity is brought to the foreground not in PiP.

What should we do in our apps to prevent/fix this behaviour? Thanks!