Move GrGLBufferImpl's GL calls to behind GrGLGpu

Move GrGLBufferImpl's GL calls to behind GrGLGpu

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/93316b92e565072e2b6fe4147802a9ffaf92eb77

[joshualitt, 2015-10-22 20:36:04]

joshualitt@google.com changed reviewers:
+ bsalomon@google.com, joshualitt@google.com, robertphillips@google.com

[joshualitt, 2015-10-22 20:36:04]

ptal, there is still atleast one odd bug when null hint is disabled.  I am open
to different approaches, but something more fine grained would unnecessarily
check the dirty state.

[bsalomon, 2015-10-22 21:37:54]

On 2015/10/22 20:36:04, joshualitt wrote:
> ptal, there is still atleast one odd bug when null hint is disabled.  I am
open
> to different approaches, but something more fine grained would unnecessarily
> check the dirty state.

I'm OK with keeping the full impls in GrGLGpu. Other than the bug, this lgtm.

[joshualitt, 2015-10-23 15:21:01]

The CQ bit was checked by joshualitt@google.com

[joshualitt, 2015-10-23 15:21:01]

The patchset sent to the CQ was uploaded after l-g-t-m from bsalomon@google.com
Link to the patchset: https://codereview.chromium.org/1417313003/#ps100001
(title: "tweaks")

[commit-bot: I haz the power, 2015-10-23 15:21:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1417313003/100001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1417313003/100001

[commit-bot: I haz the power, 2015-10-23 16:08:11]

Committed patchset #6 (id:100001) as
https://skia.googlesource.com/skia/+/93316b92e565072e2b6fe4147802a9ffaf92eb77