Enqueuing new frames in a Surface should cause Displays to reaggregate it

cc/surfaces/surface.h

Index: cc/surfaces/surface.h
diff --git a/cc/surfaces/surface.h b/cc/surfaces/surface.h
index 403d2e56baf6f8a575509050152fb4bc90bccbc8..9ab823cc50cf3626863a4a393a10b6df41dbe26a 100644
--- a/cc/surfaces/surface.h
+++ b/cc/surfaces/surface.h
@@ -5,6 +5,8 @@
 #ifndef CC_SURFACES_SURFACE_H_
 #define CC_SURFACES_SURFACE_H_
 
+#include <set>
+
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
@@ -14,6 +16,7 @@
 
 namespace cc {
 class CompositorFrame;
+class Display;
 class SurfaceManager;
 class SurfaceFactory;
 class SurfaceResourceHolder;
@@ -31,6 +34,7 @@ class CC_SURFACES_EXPORT Surface {
   const CompositorFrame* GetEligibleFrame();
 
   SurfaceFactory* factory() { return factory_; }
+  std::set<Display*>& containing_displays() { return containing_displays_; }
 
  private:
   SurfaceId surface_id_;
@@ -39,6 +43,10 @@ class CC_SURFACES_EXPORT Surface {
   // TODO(jamesr): Support multiple frames in flight.
   scoped_ptr<CompositorFrame> current_frame_;
 
+  // This is the set of Displays that used this surface the last time they
+  // drew.
+  std::set<Display*> containing_displays_;
+
   DISALLOW_COPY_AND_ASSIGN(Surface);
 };