Move NullDraw GL bindings and allow them to be disabled temporarily.

Move NullDraw GL bindings and allow them to be disabled temporarily.

This moves the NullDraw GL bindings out of generate_bindings.py to
ui/gl/gl_gl_api_implementation.cc since there are only a few methods
and this makes them easier to read, understand, and change. Add to
these methods a way to disable them causing drawing to occur. This
is needed so that one test in a test suite can disable null draw
if it wants pixel output.

TBR=piman@chromium.org
BUG=270918
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=252407

[danakj, 2014-02-20 18:41:50]

This is split out from https://codereview.chromium.org/145293007/ which previous
had a LG on this code, so TBRing it.

[danakj, 2014-02-20 19:08:23]

The CQ bit was checked by danakj@chromium.org

[commit-bot: I haz the power, 2014-02-20 19:11:20]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/165723010/30001

[commit-bot: I haz the power, 2014-02-20 22:52:10]

Change committed as 252407