For some users of SkPictureRecorder, the cull rect is more efficiently
determined while drawing is in progress, rather than when recording starts.
The existing API requires the cull rect at start time, even though the
information is not used for any culling purpose until the end of recording.
This patch provides a means to reset the cull rect when recording ends,
allowing users to update the rect based on information learned during
drawing and for the new rect to be used as the culling bound. A valid
bound is still required on the beginRecording call because
it sizes the underlying canvas and sets the aspect ratio for any bounding
box hierarchy. The bounding box factory can also be specified and parameters
that control SkPicture creation.
R=mtklein, reed1
BUG=skia:3919
Review URL: https://codereview.chromium.org/1178673007
eeff8bb8ff