[chromium] Separate concepts of scissor rect and partial swap rect

• Component: Layout and Rendering
• Status: RESOLVED WONTFIX

[Shawn Singh]

Currently the CCDamageTracker computes a damageRect that is a murky combination of scissorRect and partialSwapRect.  We should separate these two concepts, because they will not necessarily be the same rect:

1. scissorRect would be used to scissor the amount of stuff drawn to the back buffer.
2. partialSwapRect (or more generally, a collection of scissor rects that need to be swapped) would be used to swap regions of the backbuffer onto the front buffer.

When we really do make this distinction, it is probably not appropriate to keep both rects in the damage tracker.  Instead, we should create a CCPartialSwapAggregator, which retains a list of all the scissor rects that were used for drawing each frame, and uses that knowledge when the compositor asks to postSubBuffer.  It will also be far easier to test as a separate class.

[Shawn Singh]

This bug is obsolete.