Always have GrLayer's rect be valid

Always have GrLayer's rect be valid

This CL just makes atlasing easier/clearer since there is a separate atlased query method. Not using the rect as a signal also simplifies the rendering of the layer in SkGpuDevice.cpp.

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

Committed: https://skia.googlesource.com/skia/+/21048b588faa6a1c84949603ba82d9d4ba2f0cdd

[bsalomon, 2014-07-15 13:51:24]

lgtm

[robertphillips, 2014-07-15 13:54:40]

The CQ bit was checked by robertphillips@google.com

[commit-bot: I haz the power, 2014-07-15 13:54:50]

CQ is trying da patch. Follow status at

https://skia-tree-status.appspot.com/cq/robertphillips@google.com/384233002/6...

[commit-bot: I haz the power, 2014-07-15 14:09:00]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  Build-Mac10.8-Clang-x86-Release-Trybot on tryserver.skia
(http://108.170.220.76:10117/builders/Build-Mac10.8-Clang-x86-Release-Trybot/b...)
  Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Android-Trybot on tryserver.skia
(http://108.170.220.76:10117/builders/Build-Ubuntu13.10-GCC4.8-Arm7-Debug-Andr...)
  Build-Ubuntu13.10-GCC4.8-x86_64-Release-Trybot on tryserver.skia
(http://108.170.220.76:10117/builders/Build-Ubuntu13.10-GCC4.8-x86_64-Release-...)

[commit-bot: I haz the power, 2014-07-15 14:12:50]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-15 14:12:50]

Try jobs failed on following builders:
  Build-Mac10.8-Clang-x86-Release-Trybot on tryserver.skia
(http://108.170.220.76:10117/builders/Build-Mac10.8-Clang-x86-Release-Trybot/b...)

[robertphillips, 2014-07-15 14:33:55]

The CQ bit was checked by robertphillips@google.com

[commit-bot: I haz the power, 2014-07-15 14:34:10]

CQ is trying da patch. Follow status at

https://skia-tree-status.appspot.com/cq/robertphillips@google.com/384233002/8...

[commit-bot: I haz the power, 2014-07-16 02:46:39]

Change committed as 21048b588faa6a1c84949603ba82d9d4ba2f0cdd