Use GrContextFactories that produce a single GrContext in unit tests.

This is to alleviate problems due to the command buffer getting bent out of shape when the current
OpenGL context is switched out from under it (because we ran a test with a native GL context). This,
however is not a full solution. More changes will be required to ensure that after running each
command buffer or native test we bind the null context. This does allow us to take a step in that
direction without breaking anything too badly. Moreover, there is no real benefit to reusing a
GrContextFactory.

Modifies DEF_GPUTEST to take GrContextOptions rather than a factory to use. Tests were already using
their own factories anyway.

In tests that use GrContextFactory the factory instance is moved to the inner loop.

Modifies gpucts and skia_test to not use persistent GrContextFactories.

Change-Id: Ie7a36793545c775f2f30653ead6fec93a3d22717
Reviewed-on: https://skia-review.googlesource.com/71861
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
21 files changed