Linking header position to an empty entry in the recyclerView,
instead of calculating the vertical scroll position. This
allows the header to be in sync with the recyclerView scroll and
item animations
Other simplifications:
> Moving top collapse handle out of header view (it doesn't scroll)
> Removing background clipping logic from full-sheet
> Moving tab bar inside the header view
Bug: 196464142
Test: Verified on device
Change-Id: Iae5a0ae9af7ce258e1b391b8e85c5c270fe56197
Test: Go to contact bottom widgets picker. No collapse handle is
shown because the content isn't scrollable. Go to Google calendar
bottom widget picker. Collapse handle is hown because the content
is scrollable.
Bug: 185134663
Change-Id: Ic6109c055a072aa1cf3521f829833fd5f4cece0f
Only use the "app name" instead of "app name widgets" as title
Remove "Touch & hold to move a widget" subtitle.
Test: manual
Bug: 179797520
Change-Id: I7a5954af73aa5b480096e93ade3520cef6c93f17
