Add support for using glCopyTexSubImage2D when possible to copy surfaces.

Add support for using glCopyTexSubImage2D when possible to copy surfaces.
Committed: https://code.google.com/p/skia/source/detail?r=8675

[robertphillips, 2013-04-15 13:01:08]

lgtm + some nits

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp
File src/gpu/gl/GrGpuGL.cpp (right):

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp#newcod...
src/gpu/gl/GrGpuGL.cpp:2275: 
"its (non-zero) ID is returned"?

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp#newcod...
src/gpu/gl/GrGpuGL.cpp:2293: 0));
SkIRect::MakeWH?

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp#newcod...
src/gpu/gl/GrGpuGL.cpp:2311: kBGRA_8888_GrPixelConfig == src->config()) {
I find the 2nd sentence of this comment a bit confusing.

[bsalomon, 2013-04-15 13:51:01]

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp
File src/gpu/gl/GrGpuGL.cpp (right):

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp#newcod...
src/gpu/gl/GrGpuGL.cpp:2275: 
On 2013/04/15 13:01:08, robertphillips wrote:
> "its (non-zero) ID is returned"?

Done.

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp#newcod...
src/gpu/gl/GrGpuGL.cpp:2293: 0));
On 2013/04/15 13:01:08, robertphillips wrote:
> SkIRect::MakeWH?

It's a GrGLIRect

https://codereview.chromium.org/13915011/diff/1/src/gpu/gl/GrGpuGL.cpp#newcod...
src/gpu/gl/GrGpuGL.cpp:2311: kBGRA_8888_GrPixelConfig == src->config()) {
On 2013/04/15 13:01:08, robertphillips wrote:
> I find the 2nd sentence of this comment a bit confusing.
        // glCopyTexSubImage2D doesn't work with this config. We'll want to make
it a render target
        // in order to use glBlitFramebuffer or to copy to it by rendering.

[bsalomon, 2013-04-15 13:51:06]

Committed patchset #1 manually as r8675 (presubmit successful).