Use WeakPtr for posting cc tasks to main thread

Use WeakPtr for posting cc tasks to main thread

This gets rid of cc::ScopedThreadProxy in favor of using base::WeakPtr everywhere.
The semantics (should be) unchanged, the main benefit is getting rid of base::Unretained(this)
everywhere in cc.

BUG=


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=174891

[danakj, 2012-12-20 02:35:32]

Neet! LGTM

https://codereview.chromium.org/11571068/diff/2001/cc/test/layer_tree_test_co...
File cc/test/layer_tree_test_common.cc (right):

https://codereview.chromium.org/11571068/diff/2001/cc/test/layer_tree_test_co...
cc/test/layer_tree_test_common.cc:340:
m_layerTreeHost->proxy()->mainThread()->postTask(base::Bind(&ThreadedTest::realEndTest,
m_mainThreadWeakPtr));
nit: proxy() directly like the others?

[nduca, 2012-12-20 18:48:46]

LGTM. It seems to me that the next logical step is to split the thread proxy
into to proxy and proxyimpl both of which SupportWeakPtr.

[commit-bot: I haz the power, 2013-01-02 21:34:12]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jamesr@chromium.org/11571068/8001

[commit-bot: I haz the power, 2013-01-02 23:59:51]

Change committed as 174891