Make GrLayerCache use multiple plots in its atlas

Make GrLayerCache use multiple plots in its atlas

Until we have a recycling Rectanizer the atlas purging must occur at the GrPlot level. This CL breaks the atlas into four plots to give some room for purging (without trashing the entire atlas).

This is calved off of (Add atlased layer purging - https://codereview.chromium.org/367073002/)

Committed: https://skia.googlesource.com/skia/+/261b8a98dc7378989ba8fa9c06b728e89162862b

[jvanverth1, 2014-07-16 21:04:16]

https://codereview.chromium.org/397873004/diff/60001/src/gpu/GrLayerCache.cpp
File src/gpu/GrLayerCache.cpp (right):

https://codereview.chromium.org/397873004/diff/60001/src/gpu/GrLayerCache.cpp...
src/gpu/GrLayerCache.cpp:45: *  PictureKey just wraps a picture's unique ID for
GrTHashTable. It is used to
I don't think we're supposed to use GrTHashTable any more.

[robertphillips, 2014-07-17 11:57:45]

https://codereview.chromium.org/397873004/diff/60001/src/gpu/GrLayerCache.cpp
File src/gpu/GrLayerCache.cpp (right):

https://codereview.chromium.org/397873004/diff/60001/src/gpu/GrLayerCache.cpp...
src/gpu/GrLayerCache.cpp:45: *  PictureKey just wraps a picture's unique ID for
GrTHashTable. It is used to
Why don't I do that as a separate CL and just eliminate it all at once.

[jvanverth1, 2014-07-17 15:14:45]

lgtm

[robertphillips, 2014-07-17 15:15:08]

The CQ bit was checked by robertphillips@google.com

[commit-bot: I haz the power, 2014-07-17 15:16:02]

CQ is trying da patch. Follow status at

https://skia-tree-status.appspot.com/cq/robertphillips@google.com/397873004/6...

[commit-bot: I haz the power, 2014-07-17 15:26:49]

Change committed as 261b8a98dc7378989ba8fa9c06b728e89162862b