Remove the problematic call to GLSurface::GetBackingFrameBufferObject.

Remove the problematic call to GLSurface::GetBackingFrameBufferObject.

GLContextVirtual::IsCurrent doesn't need to call
GetBackingFrameBufferObject on a surface, the IsOffScreen check should
be enough.

The direct reason for this change is that GLContextVirtual::IsCurrent's
use of GetBackingFrameBufferObject interferes with the implementation of
that function in TextureImageTransportSurface.
TextureImageTransportSurface::GetBackingFrameBufferObject creates an FBO
if needed. Unfortunately GLContextVirtual::IsCurrent is called early in
GLContextVirtual's initialization, too early for
TextureImageTransportSurface::GetBackingFrameBufferObject to create the
frame buffer object because it needs a fully initialized context to
succeed.

BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=222505

[no sievers, 2013-09-09 17:04:12]

lgtm

https://codereview.chromium.org/23480048/diff/1/gpu/command_buffer/service/gl...
File gpu/command_buffer/service/gl_context_virtual.cc (right):

https://codereview.chromium.org/23480048/diff/1/gpu/command_buffer/service/gl...
gpu/command_buffer/service/gl_context_virtual.cc:73: if (surface &&
nit: I think this fits in one line now

[piman, 2013-09-09 21:08:37]

lgtm

[commit-bot: I haz the power, 2013-09-10 05:50:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msimonides@opera.com/23480048/1

[commit-bot: I haz the power, 2013-09-10 07:27:08]

Retried try job too often on mac_rel for step(s) telemetry_unittests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

[commit-bot: I haz the power, 2013-09-10 07:51:56]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msimonides@opera.com/23480048/1

[commit-bot: I haz the power, 2013-09-10 08:36:27]

Retried try job too often on mac_rel for step(s) telemetry_unittests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

[commit-bot: I haz the power, 2013-09-10 09:01:56]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msimonides@opera.com/23480048/1

[commit-bot: I haz the power, 2013-09-10 09:57:34]

Retried try job too often on mac_rel for step(s) telemetry_unittests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=mac_rel&nu...

[commit-bot: I haz the power, 2013-09-11 07:57:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msimonides@opera.com/23480048/1

[commit-bot: I haz the power, 2013-09-11 12:10:53]

Change committed as 222505