Proxy the PPP_Printing interface

ppapi/shared_impl/resource_tracker.h

Index: ppapi/shared_impl/resource_tracker.h
diff --git a/ppapi/shared_impl/resource_tracker.h b/ppapi/shared_impl/resource_tracker.h
index b58541382a483661af7747d29417c1781a097904..6a926ccc58fc78e495a025c4deeb101e3cfd45bc 100644
--- a/ppapi/shared_impl/resource_tracker.h
+++ b/ppapi/shared_impl/resource_tracker.h
@@ -10,6 +10,7 @@
 #include "base/basictypes.h"
 #include "base/hash_tables.h"
 #include "base/memory/linked_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
@@ -30,6 +31,9 @@ class PPAPI_SHARED_EXPORT ResourceTracker {
   void AddRefResource(PP_Resource res);
   void ReleaseResource(PP_Resource res);
 
+  // Releases a reference on the given resource once the message loop returns.
+  void ReleaseResourceSoon(PP_Resource res);
+
   // Notifies the tracker that a new instance has been created. This must be
   // called before creating any resources associated with the instance.
   void DidCreateInstance(PP_Instance instance);
@@ -90,6 +94,8 @@ class PPAPI_SHARED_EXPORT ResourceTracker {
 
   int32 last_resource_value_;
 
+  base::WeakPtrFactory<ResourceTracker> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(ResourceTracker);
 };