cc: Block commit on activate by setting a flag on LayerTreeHost.

cc/layers/tiled_layer.cc

Index: cc/layers/tiled_layer.cc
diff --git a/cc/layers/tiled_layer.cc b/cc/layers/tiled_layer.cc
index 556b823147a5c8cf67c0432c3a4076bafbd31a5c..c73979b772a1c25c7a6bcedc9e5c29df2d1efed6 100644
--- a/cc/layers/tiled_layer.cc
+++ b/cc/layers/tiled_layer.cc
@@ -235,8 +235,6 @@ void TiledLayer::PushPropertiesTo(LayerImpl* layer) {
   needs_push_properties_ = true;
 }
 
-bool TiledLayer::BlocksPendingCommit() const { return true; }

[enne (OOO), 2013/08/29 20:01:33]

I don't think this is safe to just remove.

[enne (OOO), 2013/08/29 20:03:22]

Or, it seems unlikely that anybody would stick a TiledLayer into an impl-side
painting tree, but if they did TiledLayer really doesn't support that.  So,
there either needs to be some safety here via blocking commits or a CHECK or
something?

[danakj, 2013/08/29 20:13:52]

Unit tests do it, but they all pass. So I was like *shrug*. But okay I'll make
this layer set the bit in Update().

[enne (OOO), 2013/08/29 20:19:10]

...

I think partial updates would be very wrong with impl-side painting.  Mostly,
it's that this path isn't tested very well, so I'd prefer to avoid it entirely.

-
 PrioritizedResourceManager* TiledLayer::ResourceManager() {
   if (!layer_tree_host())
     return NULL;