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

cc/surfaces/surface_manager.h

Index: cc/surfaces/surface_manager.h
diff --git a/cc/surfaces/surface_manager.h b/cc/surfaces/surface_manager.h
index 40e55f1fc7ee1f522b550cb392fe6e79f7ca2399..e029760a98573767f19b3bfc03b7497aeed36639 100644
--- a/cc/surfaces/surface_manager.h
+++ b/cc/surfaces/surface_manager.h
@@ -5,8 +5,11 @@
 #ifndef CC_SURFACES_SURFACE_MANAGER_H_
 #define CC_SURFACES_SURFACE_MANAGER_H_
 
+#include <set>
+
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
 
@@ -24,9 +27,25 @@ class CC_SURFACES_EXPORT SurfaceManager {
 
   Surface* GetSurfaceForId(SurfaceId surface_id);
 
+  class CC_SURFACES_EXPORT SurfaceDamageObserver {

[jamesr, 2014/08/11 16:58:02]

no export needed, this doesn't have any symbols to export

inner classes are pretty annoying (can't forward declare them) and the double
'Surfaces' in the name SurfaceManager::SurfaceDamageObserver is kind of
annoying. can you make this a standalone interface in its own header?

+   public:
+    virtual void OnSurfaceDamaged(SurfaceId surface_id) = 0;
+  };
+
+  void AddObserver(SurfaceDamageObserver* obs) {
+    observer_list_.AddObserver(obs);
+  }
+
+  void RemoveObserver(SurfaceDamageObserver* obs) {
+    observer_list_.RemoveObserver(obs);
+  }
+
+  void SurfaceModified(SurfaceId surface_id);
+
  private:
   typedef base::hash_map<SurfaceId, Surface*> SurfaceMap;
   SurfaceMap surface_map_;
+  ObserverList<SurfaceDamageObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceManager);
 };