Mac Overlays: Add sandwich strategy

cc/output/gl_renderer.cc

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/gl_renderer.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 3504 matching lines @@
   if (!frame->overlay_list.size())
     return;
 
   ResourceProvider::ResourceIdArray resources;
   OverlayCandidateList& overlays = frame->overlay_list;
   for (const OverlayCandidate& overlay : overlays) {
     // Skip primary plane.
     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);
   }
 }
 
 }  // namespace cc