Request scroll capture when the screen rotates.

Show/hide the scroll capture button based upon availability of
scrollable content in the underlying app.

Needed a little delay after rotation to allow the underlying app to
adjust to the new orientation (otherwise it was always not scrollable).

Bug: 185897865
Test: Take screenshot, observe capture more, rotate, tap capture more.
Test: Take screenshot of an activity that scrolls in portrait but not
      landcape, rotate the phone and observe the capture more button
      appearing and disappearing appropriately.
Change-Id: I0015adee77e576549509468486936c57ec62a2fd