Decouple cc::FakeWebGraphicsContext3D from blink::WGC3D

Decouple cc::FakeWebGraphicsContext3D from blink::WGC3D

cc_unittests that do not need a real OpenGL context use a stubbed-out
context provided by cc::TestGLES2Interface that forwards to a cc::TestWebGraphicsContext3D
stub that is subclassed by various unit tests. This makes cc::TWGC3D no longer subclass
blink::WebGraphicsContext3D to cut down on the blink dependency. This will enable moving
the test code to derive from TestGLES2Interface more directly down the road to cut out
the intermediates.

One subtle consequence of this change is that now that no class in the blink namespace is
in the inheritance chain for the test context subclasses, the clang checker now requires
OVERRIDE annotations.

BUG=181120
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=244152

[danakj, 2014-01-09 23:25:51]

LGTM

https://codereview.chromium.org/126973002/diff/80001/cc/test/test_context_pro...
File cc/test/test_context_provider.cc (right):

https://codereview.chromium.org/126973002/diff/80001/cc/test/test_context_pro...
cc/test/test_context_provider.cc:96: return NULL;
can you NOTREACHED()? maybe it will help maybe not

[jamesr, 2014-01-10 01:02:29]

https://codereview.chromium.org/126973002/diff/80001/cc/test/test_context_pro...
File cc/test/test_context_provider.cc (right):

https://codereview.chromium.org/126973002/diff/80001/cc/test/test_context_pro...
cc/test/test_context_provider.cc:96: return NULL;
On 2014/01/09 23:25:51, danakj wrote:
> can you NOTREACHED()? maybe it will help maybe not

This getter is going away in https://codereview.chromium.org/132163004/ so I
don't think it matters too much.

[commit-bot: I haz the power, 2014-01-10 01:24:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jamesr@chromium.org/126973002/130002

[commit-bot: I haz the power, 2014-01-10 12:05:05]

Change committed as 244152