Restore gl scissor state when switching FBO targets on Qualcomm

Restore gl scissor state when switching FBO targets on Qualcomm

This works around flickering on Qualcomm devices when
using virtual contexts. Qualcomm has a bug where switching
to FBO targets of different sizes corrupts the scissor rect.

BUG=165493
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=175630

[brianderson, 2013-01-04 22:00:56]

https://codereview.chromium.org/11734037/diff/1/ui/gl/gl_gl_api_implementatio...
File ui/gl/gl_gl_api_implementation.cc (right):

https://codereview.chromium.org/11734037/diff/1/ui/gl/gl_gl_api_implementatio...
ui/gl/gl_gl_api_implementation.cc:115: bool switched_surfaces =
GLSurface::GetCurrent() != surface;
Note:

This comparison is almost always false because I'm comparing the "real" surface
to the "virtual" surface, so this patch almost always restores the state on a
MakeCurrent.

That's a bit more often than I intended.

Other parts of the function compare these two surfaces though, which is where my
confusion came from.

Will need to figure out how to narrow down which case we need to restore the
state.  I'm not sure it's easy to detect FBO target changes from here.  Even if
we could detect it here, it'll probably be too late.

[greggman, 2013-01-08 18:24:44]

lgtm

[commit-bot: I haz the power, 2013-01-08 18:29:25]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brianderson@chromium.org/11734037/4001

[commit-bot: I haz the power, 2013-01-08 18:32:49]

Step "update" is always a major failure.
Look at the try server FAQ for more details.

[commit-bot: I haz the power, 2013-01-08 20:40:03]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/brianderson@chromium.org/11734037/4001

[commit-bot: I haz the power, 2013-01-09 00:27:47]

Change committed as 175630