Mac Overlays: Add sandwich strategy

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index a89c33d140c8eab3123b0ae65c0b3a6aaa344f50..3357640e41227bd9bba538ecf0e6e0afe225e0d6 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -3522,16 +3522,19 @@ void GLRenderer::ScheduleOverlays(DrawingFrame* frame) {
     if (overlay.plane_z_order == 0)
       continue;
 
-    pending_overlay_resources_.push_back(
-        make_scoped_ptr(new ResourceProvider::ScopedReadLockGL(
-            resource_provider_, overlay.resource_id)));
+    unsigned texture_id = 0;

[ccameron, 2015/08/23 21:29:05]

This is the bit where we pull the texture out from the OutputSurface. If we
handled the primary plane here, this would be simpler (is there a reason we
don't -- could we pack more stuff in the RendererState so that we could create a
complete description of the primary plane and unify all of this? or is there
something more going on?).

[alexst (slow to review), 2015/08/24 15:07:02]

Some background. In theory, we could have overlays with a regular old egl
surface. In that case, we don't really have a resource or texture for the
primary plane, so we assume the gpu process knows how to get it lower in the
platform and we only schedule overlays.

With surfaceless, which is what osx and cros are now using, we do have a
resource for the primary plane, and I think it probably makes sense to refactor
things a bit so that it shows up here along with other overlay planes instead of
being scheduled separately. 

There is nothing fancy going on, just that this code existed before surfaceless.

+    if (overlay.use_output_surface_for_resource) {
+      texture_id = output_surface_->GetOverlayTextureId();
+    } else {
+      pending_overlay_resources_.push_back(
+          make_scoped_ptr(new ResourceProvider::ScopedReadLockGL(
+              resource_provider_, overlay.resource_id)));
+      texture_id = pending_overlay_resources_.back()->texture_id();
+    }
 
     context_support_->ScheduleOverlayPlane(
-        overlay.plane_z_order,
-        overlay.transform,
-        pending_overlay_resources_.back()->texture_id(),
-        ToNearestRect(overlay.display_rect),
-        overlay.uv_rect);
+        overlay.plane_z_order, overlay.transform, texture_id,
+        ToNearestRect(overlay.display_rect), overlay.uv_rect);
   }
 }