Allow WebExternalTextureLayerClient to work with mailboxes.

cc/texture_layer.cc

Index: cc/texture_layer.cc
diff --git a/cc/texture_layer.cc b/cc/texture_layer.cc
index ffb22ac0ed9dee71993e9b3afe0befd5a93650e5..b60a6477d71d11797a398bd22c107072a0af1a31 100644
--- a/cc/texture_layer.cc
+++ b/cc/texture_layer.cc
@@ -26,12 +26,9 @@ static void PostCallbackToMainThread(
       base::Bind(&RunCallbackOnMainThread, callback, sync_point));
 }
 
-scoped_refptr<TextureLayer> TextureLayer::Create(TextureLayerClient* client) {
-  return scoped_refptr<TextureLayer>(new TextureLayer(client, false));
-}
-
-scoped_refptr<TextureLayer> TextureLayer::CreateForMailbox() {
-  return scoped_refptr<TextureLayer>(new TextureLayer(NULL, true));
+scoped_refptr<TextureLayer> TextureLayer::Create(TextureLayerClient* client,
+                                                 bool usesMailbox) {

[piman, 2013/03/14 19:54:58]

nit: uses_mailbox

[alexst (slow to review), 2013/03/14 20:37:06]

Done.

+  return scoped_refptr<TextureLayer>(new TextureLayer(client, usesMailbox));
 }
 
 TextureLayer::TextureLayer(TextureLayerClient* client, bool uses_mailbox)
@@ -158,7 +155,13 @@ void TextureLayer::Update(ResourceUpdateQueue* queue,
                           const OcclusionTracker* occlusion,
                           RenderingStats* stats) {
   if (client_) {
-    texture_id_ = client_->prepareTexture(*queue);
+    if (uses_mailbox_) {
+      TextureMailbox mailbox;
+      if (client_->prepareTextureMailbox(&mailbox))
+        SetTextureMailbox(mailbox);

[piman, 2013/03/14 19:54:58]

How hard would it be to change the BrowserPluginCompositingHelper to use the
TextureLayerClient::prepareTextureMailbox path, and then make SetTextureMailbox
private? It would be nice to have a single mailbox path.

As we remove the non-mailbox users, I'm sure we can shortly remove the
SetTextureId path, and possibly even the non-mailbox paths in a nearish future -
basically streamlining the code paths.

[alexst (slow to review), 2013/03/14 20:37:06]

Shouldn't be too bad, I'll look into it.

As far as removing SetTextureId path, once the rest of the canvas code is using
mailboxes, I think browser compositor is the last user, so it should be doable.

+    } else {
+      texture_id_ = client_->prepareTexture(*queue);
+    }
     context_lost_ =
         client_->context()->getGraphicsResetStatusARB() != GL_NO_ERROR;
   }