cc: Introduce embedded_surfaces in metadata for surface Ids in draw quads

cc/output/compositor_frame_metadata.h

Index: cc/output/compositor_frame_metadata.h
diff --git a/cc/output/compositor_frame_metadata.h b/cc/output/compositor_frame_metadata.h
index 98bed560715476f4dc71382cdc383574ba08b86b..12d7bf5c5b69c08183036866fc3939dc8ff791a6 100644
--- a/cc/output/compositor_frame_metadata.h
+++ b/cc/output/compositor_frame_metadata.h
@@ -77,8 +77,15 @@ class CC_EXPORT CompositorFrameMetadata {
   std::vector<ui::LatencyInfo> latency_info;
 
   // This is the set of Surfaces that are referenced by this frame.
+  // Note: this includes occluded and clipped surfaces and surfaces that may
+  // be accessed by this CompositorFrame in the future.
+  // TODO(fsamuel): This should go away once generalized frame eviction is

[danakj, 2017/04/07 16:41:17]

It'd be nice to explain /why/ this should go away

[Fady Samuel, 2017/04/07 17:16:26]

Done.

+  // implemented.
   std::vector<SurfaceId> referenced_surfaces;
 
+  // This is the set of SurfaceIds embedded in DrawQuads.
+  std::vector<SurfaceId> embedded_surfaces;
+
   // This indicates whether this CompositorFrame can be activated before
   // dependencies have been resolved.
   bool can_activate_before_dependencies = true;