cc: Provide notifications when resources are available.

cc: Provide notifications when resources are available.

The DelegatedRendererLayer collects unused resources, but we'd like
the embedder to know when resources are available for it to pick up.
This adds a callback to inform the embedder when resources are
available.

Tested by new conditions in all the LayerTreeHostDelegatedTests.

R=piman
BUG=263069
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=224923

[danakj, 2013-09-23 21:56:27]

This adds the callback, but does not use it on RWHVA. I don't know how to expose
this nicely to RWHVA since it uses ui::Layer which can be all these different
types.

Do I set a DelegatedRendererLayerClient* on ui::Layer before setting any
delegated frames, and then use that client heceforth? How would you expose it?

[piman, 2013-09-23 22:28:57]

LGTM. I think we want to expose it through ui::Layer, since that's the one
that's managing the cc::Layer. We try not to expose too much of cc outside of
ui::Layer anyway, Law of Demeter and all that.

[commit-bot: I haz the power, 2013-09-23 22:40:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/24303008/4001

[commit-bot: I haz the power, 2013-09-24 06:39:40]

Change committed as 224923