Fix error in Ganesh' tiled bitmap drawing

When the paint filter level is high ShouldUseBicubic doesn't always return true. In this case the paint's filter level will differ from the filtering Ganesh will use. This was leading to a mismatch between the tiling computed in SkGpuDevice::drawBitmapCommon and the one in SkGpuDevice::drawTiledBitmap.

The end result of this was that the max texture restriction could be violated which is currently being seen on the Xoom & N7 bots. Both of them have a max texture size of 2048 which is invoking the tiled drawbitmap case.

Review URL: https://codereview.chromium.org/752623002
clarify samplecount field in imagegpu

BUG=skia:
TBR=bsalomon

Review URL: https://codereview.chromium.org/750023002
SkData -> SkPicture::SnapshotArray

Restores type safety with all the same features.

(Also note, less code: 29 insertions, 50 deletions.)

BUG=skia:

Review URL: https://codereview.chromium.org/746553002
public SkNVRefCnt<SnapshotArray>

Should fix broken build.

NOTRY=true
TBR=reed@google.com

BUG=skia:

Review URL: https://codereview.chromium.org/748143002