Remove QuadCuller class and make QuadSink concrete

Remove QuadCuller class and make QuadSink concrete

Make the base class QuadSink concrete instead of pure virtual, and
remove QuadCuller class. Testing class MockQuadCuller is still derived
from QuadSink, which also manipulates its own MockOcclusionTracker.

This CL is part of clean up QuadSink. Next step would to plum LayerImpl
through so QuadSink will no longer need to hold that variable, in order
to split up QuadSink into just RenderPass and OcclusionTracker.

This CL follows 302603006 and 306683002.

BUG=344962
TEST=cc_unittests

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=277788

[enne (OOO), 2014-05-30 21:36:35]

lgtm.  Feel free to just collapse this along with the next patch
(https://codereview.chromium.org/304203005/) so that you can just remove the
LayerImpl pointer rather than moving it around.

[weiliangc, 2014-06-17 16:15:14]

The CQ bit was checked by weiliangc@chromium.org

[commit-bot: I haz the power, 2014-06-17 16:16:07]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/weiliangc@chromium.org/309493002/80001

[commit-bot: I haz the power, 2014-06-17 17:03:58]

Change committed as 277788