Proposed SkCanvas API for preLoading textures to VRAM v2.0

Proposed SkCanvas API for preLoading textures to VRAM v2.0

This is an update to (Proposed SkCanvas API for preLoading textures to VRAM - https://codereview.chromium.org/192853002/). It takes into account in-person feedback on the initial proposal. The main feedback was to land this closer to where we will ultimately wind up with the reordered rendering capability (and don't have an SkCanvas entry point (yet)).

Committed: http://code.google.com/p/skia/source/detail?r=13810

R=reed@google.com, bsalomon@google.com

Author: robertphillips@google.com

Review URL: https://codereview.chromium.org/197123003

git-svn-id: http://skia.googlecode.com/svn/trunk@13822 2bbb7eff-a529-9590-31e7-b0007b416f81