Add code for new invalidation local ack system

sync/notifier/mock_ack_handler.h

Index: sync/notifier/mock_ack_handler.h
diff --git a/sync/notifier/mock_ack_handler.h b/sync/notifier/mock_ack_handler.h
new file mode 100644
index 0000000000000000000000000000000000000000..665955892bfd60803b1e429db781694471ae4d4b
--- /dev/null
+++ b/sync/notifier/mock_ack_handler.h
@@ -0,0 +1,64 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SYNC_NOTIFIER_MOCK_ACK_HANDLER_H_
+#define SYNC_NOTIFIER_MOCK_ACK_HANDLER_H_
+
+#include <vector>
+
+#include "base/compiler_specific.h"
+#include "base/memory/weak_ptr.h"
+#include "sync/base/sync_export.h"
+#include "sync/internal_api/public/util/weak_handle.h"
+#include "sync/notifier/ack_handler.h"
+
+namespace syncer {
+
+class Invalidation;
+
+// This AckHandler implementation colaborates with the FakeInvalidationService
+// to enable unit tests to assert that invalidations are being acked properly.
+class MockAckHandler
+  : public AckHandler,
+    public base::SupportsWeakPtr<MockAckHandler> {
+ public:
+  MockAckHandler();
+  virtual ~MockAckHandler();
+
+  // Sets up some internal state to track this invalidation, and modifies it so
+  // that its Acknowledge() and Drop() methods will route back to us.
+  void RegisterInvalidation(Invalidation* invalidation);
+
+  // No one was listening for this invalidation, so no one will receive it or
+  // ack it.  We keep track of it anyway to let tests make assertions about it.
+  void RegisterUnsentInvalidation(Invalidation* invalidation);
+
+  // Returns true if the specified invalidaition has been delivered, but has not
+  // been acknowledged yet.
+  bool IsUnacked(const Invalidation& invalidation) const;
+
+  // Returns true if the specified invalidation was never delivered.
+  bool IsUnsent(const Invalidation& invalidation) const;
+
+  // Implementation of AckHandler.
+  virtual void Acknowledge(
+      const invalidation::ObjectId& id,
+      const AckHandle& handle) OVERRIDE;
+  virtual void Drop(
+      const invalidation::ObjectId& id,
+      const AckHandle& handle) OVERRIDE;
+
+ private:
+  typedef std::vector<syncer::Invalidation> InvalidationVector;
+
+  WeakHandle<AckHandler> WeakHandleThis();
+
+  InvalidationVector unsent_invalidations_;
+  InvalidationVector unacked_invalidations_;
+  InvalidationVector acked_invalidations_;
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_NOTIFIER_MOCK_ACK_HANDLER_H_