Add code for new invalidation local ack system

sync/internal_api/public/base/invalidation.h

Index: sync/internal_api/public/base/invalidation.h
diff --git a/sync/internal_api/public/base/invalidation.h b/sync/internal_api/public/base/invalidation.h
index 4e157e0597172126df0fcbdaae41f52799d7f0a9..1d7b500507497684e1f21fa51502985ec3fa9a23 100644
--- a/sync/internal_api/public/base/invalidation.h
+++ b/sync/internal_api/public/base/invalidation.h
@@ -54,14 +54,12 @@ class SYNC_EXPORT Invalidation {
   // TODO(rlarocque): Remove this method and use AckHandlers instead.
   void set_ack_handle(const AckHandle& ack_handle);
 
+  // Functions from the alternative ack tracking framework.
+  // Currently unused.
   void set_ack_handler(syncer::WeakHandle<AckHandler> ack_handler);
-
-  // True if this class has a valid AckHandler.
   bool SupportsAcknowledgement() const;
-
-  // TODO(rlarocque): Re-enable these when we switch to AckHandlers.
-  // void Acknowledge() const;
-  // void Drop(DroppedInvalidationTracker* tracker) const;
+  void Acknowledge() const;
+  void Drop(DroppedInvalidationTracker* tracker) const;

[tim (not reviewing), 2013/10/29 17:21:57]

Comment param.

[rlarocque, 2013/10/30 00:49:26]

Done.

 
   scoped_ptr<base::DictionaryValue> ToValue() const;
   std::string ToString() const;