Ensure overdraw, not overdraw, of reused bitmaps

Rounding errors should tilt toward a 1 pixel overdraw. These
errors could occur because the application of a scaling matrix
is opaque to caller within Canvas, and underdrawing can result
in garbage pixels in an extra line. Also added verbose logging.

Bug: 17963089
Change-Id: Id85b50ee646aecdcb7d6b26bd988577bc6fec980
Add a simple fullscreen activity for flickr sample
Fix still gifs failing to decode.

Fixes #196.