Cherry-pick: cc: Avoid redraw for missing tile outside visible rect

Cherry-pick with conflict of crrev.com/r290937

Conflicts:
	cc/layers/picture_layer_impl.cc

BUG: 17033041

Original description:

Tiles outside of the visible rect for tile priority but
inside the draw viewport should be drawn on a best effort
basis. There is no need to redraw or block activations on
missing or incomplete tiles in this region.

Rename tile priority rect/matrix to activation rect, and
use this to control activation as well. Add new counts for
missing/incomplete tiles in the activation rect, and only
these tiles will lead to redraws.

Change-Id: I44ebf9905dab38e042f3f990890a1acdb0ad41ab
4 files changed