Start of hardware overlay support in CC with Ubercompositor.

cc/quads/render_pass.h

Index: cc/quads/render_pass.h
diff --git a/cc/quads/render_pass.h b/cc/quads/render_pass.h
index 4285e53010311d27d7b4fd58ddb70f81b15354c0..934ea9018c0c8d2e65b5075f9b1252874ee466ec 100644
--- a/cc/quads/render_pass.h
+++ b/cc/quads/render_pass.h
@@ -62,6 +62,8 @@ class CC_EXPORT RenderPass {
     }
   };
 
+  enum HwOverlayState { NO_OVERLAY, RENDER_AND_OVERLAY, SIMPLE_OVERLAY, };

[enne (OOO), 2014/03/14 18:13:41]

bikeshed: maybe just OverlayState? Are there other kinds of overlays?

+
   ~RenderPass();
 
   static scoped_ptr<RenderPass> Create();
@@ -111,6 +113,11 @@ class CC_EXPORT RenderPass {
   QuadList quad_list;
   SharedQuadStateList shared_quad_state_list;
 
+  // Specifies whether the pass is going into an overlay, needs to be rendered
+  // into a buffer before it can be presented to overlay hardware or a quad
+  // inside it is presented as is.

[piman, 2014/03/14 03:42:34]

nit: this would be a great comment to have on the enum rather than here.

+  HwOverlayState overlay_state;

[piman, 2014/03/14 03:42:34]

Generally, adding a field here requires it to be added to
ParamTraits<cc::RenderPass> in cc_messages.cc (and also to corresponding tests).

That said, in this case I'm not sure we'd ever want to IPC the value of this
field. If not indeed, we should simply add a DCHECK in
ParamTraits<cc::RenderPass>::Write that it's the default value.

[alexst (slow to review), 2014/03/14 19:54:22]

Yes, this should only exist in one process. I added a DCHECK, thank you for
noting that.

+
  protected:
   explicit RenderPass(size_t num_layers);
   RenderPass();