Reland of Revert of gpu: introduce glCopySubTextureCHROMIUM (patchset #1 id:1 of https://codereview.chromium.org/972833004/)

Reason for revert:
Fix OSX failure. glValidateProgram() in OSX has very strange behavior. It validates FBO unexpectedly.
So glValidateProgram() falsely fails if FBO is not bound. Move the validation code after FBO binding.
In addition, previous patch hits one-copy performance badly because CopySubTextureCHROMIUM
didn't use image copy optimization like CopyTextureCHROMIUM. This CL applied it.

Original issue's description:
> Revert of gpu: introduce glCopySubTextureCHROMIUM (patchset #4 id:80001 of https://codereview.chromium.org/864513004/)
>
> Reason for revert:
> This broke telemetry_unittests and content_browsertests on Mac (see issue 463439)
>
> Original issue's description:
> > gpu: introduce glCopySubTextureCHROMIUM
> >
> > Introduce glCopySubTextureCHROMIUM to support immutable texture as well as to
> > optimize WebGL texSubImage2D(video | canvas).
> >
> > This CL changes gl_renderer to use glCopySubTextureCHROMIUM because the
> > destination texture is immutable.
> >
> > TEST=GLCopyTextureCHROMIUMTest
> > BUG=443151
> >
> > Committed: https://crrev.com/fac6a2d44323ad51429ee728e241fe22242f5ebd
> > Cr-Commit-Position: refs/heads/master@{#318855}
>
> TBR=sievers@chromium.org,piman@chromium.org,kbr@chromium.org,zmo@chromium.org,scherkus@chromium.org,dongseong.hwang@intel.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=443151
>
> Review URL: https://codereview.chromium.org/972833004
>
> Cr-Commit-Position: refs/heads/master@{#318858}

BUG=443151, 463439

Review URL: https://codereview.chromium.org/977853002

Cr-Commit-Position: refs/heads/master@{#319288}

0 files changed, 0 insertions, 0 deletions