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
26 files changed