Added a RenderBuffer/RenderBufferInterface getTextureStorage method.

Change-Id: I710fba737524e735349ce1c0b09fa535555bd029
Reviewed-on: https://chromium-review.googlesource.com/177034
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Commit-Queue: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>
2 files changed