tree 8bcc4cddb93ad2ef436cceebe49db339759c5922
parent 42144fae221a0a2f689f01d443eaed9cc45c511c
author Dake Gu <dake@google.com> 1477616289 -0700
committer Dake Gu <dake@google.com> 1478208598 -0700

Rework background manager and add TestCases

1. Simplify background layerDrawable from 5 layers to 2 layers.
   Especially disable the DimLayer to reduce graphics burden.
2. Made release() in onStop() a default behavior to reduce
   possible memory growing.
3. Top activity will inherit background from bottom activity,
   but not the other way. This fixes the problem that BrowseActivity
   inherits DetailsActivity's parallax background after returns from
   it.
5. Add convenient method to query selected item in BrowseFragment.
6. updated samples to handle background change in opening/closing
   header fragment and reapply background when returning to the
   activity (onStart)
7. Added new BackgroundManagerTest

Bug: 32415435
Test: BackgroundManagerTest

Change-Id: I93a026d3e1437c93e22cf0a2fa456d0b3e5f15b7