Plumb overlay processing into DirectRenderer.

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 55dafbd47d20e36196a8924b800c97cbbc9191db..869e118b88ac26ce07b43ab55c37a7948bf26b6f 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -1453,6 +1453,10 @@ void ResourceProvider::DeclareUsedResourcesFromChild(
        it != child_info.child_to_parent_map.end();
        ++it) {
     ResourceId local_id = it->second;
+    // Hold onto resources that still have read locks on them.
+    if (GetResource(local_id)->lock_for_read_count > 0)
+      child_info.in_use_resources.insert(local_id);

[piman, 2014/03/27 00:12:37]

I'm not sure if it's the best way to do this, in particular it means we have to
wait one more frame before returning the resources after the swap (since we have
to wait for the next DeclareUsedResourcesFromChild, on the next commit, and that
might even be skipped if the layer didn't change).

What I had in mind rather, is to follow the places where we test exported_count,
and take lock_for_read_count into account there too, where it makes sense.
Specifically, DeleteAndReturnUnusedResourcesToChild would mark for deletion
(instead of deleting immediately), and conversely, UnlockForRead would call
DeleteResourceInternal or DeleteAndReturnUnusedResourcesToChild if the resource
was marked_for_deletion and the lock_for_read_count dropped to 0.

Possibly doing the same for DeleteResource, if we ever want to handle the case
where the overlay candidate comes directly from the UI compositor.

+
     bool resource_is_in_use = child_info.in_use_resources.count(local_id) > 0;
     if (!resource_is_in_use)
       unused.push_back(local_id);