sync: Inject sync/'s dependency on invalidations

sync/test/trackable_mock_invalidation.h

Index: sync/test/trackable_mock_invalidation.h
diff --git a/sync/test/trackable_mock_invalidation.h b/sync/test/trackable_mock_invalidation.h
new file mode 100644
index 0000000000000000000000000000000000000000..1ad3697e16fae029b34f4721835108ebc99a3220
--- /dev/null
+++ b/sync/test/trackable_mock_invalidation.h
@@ -0,0 +1,54 @@
+// Copyright 2014 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_TEST_TRACKABLE_MOCK_INVALIDATION_H_
+#define SYNC_TEST_TRACKABLE_MOCK_INVALIDATION_H_
+
+#include "sync/test/mock_invalidation.h"
+
+namespace syncer {
+
+class MockInvalidationTracker;
+
+// A variant of MockInvalidation that supports acknowledgements.
+//
+// With the help of a MockInvalidationTracker, this can be used to test
+// sync's use of the Drop() and Acknowledge() methods.
+class TrackableMockInvalidation : public MockInvalidation {
+ public:
+  TrackableMockInvalidation(bool is_unknown_version,
+                            int64 version,
+                            const std::string& payload,
+                            MockInvalidationTracker* tracker,
+                            int tracking_id);
+  virtual ~TrackableMockInvalidation();
+
+  // Forwards notice of the acknowledgement of this invalidation to the
+  // |tracker_|.
+  virtual void Acknowledge() OVERRIDE;
+
+  // Forwards notice of the drop of this invalidation to the |tracker_|.
+  virtual void Drop() OVERRIDE;
+
+  // Returns the integer used to identify this object with the |tracker_|.
+  int GetTrackingId();
+
+ private:
+  // The MockInvalidationTracker that initialized this object, and which keeps
+  // track of its acknowledgement status.  It is expected to outlive the
+  // invalidations.  The data required for unit test assertions lives there.
+  MockInvalidationTracker* tracker_;
+
+  // An identifier that uniquely identifies this invalidation to its
+  // |tracker_|.
+  //
+  // This is necessary in part because invalidations may be short lived; the
+  // invalidation may be deleted by the time we want to make assertions about
+  // its state.
+  int tracking_id_;
+};
+
+}  // namespace syncer
+
+#endif  // SYNC_TEST_TRACKABLE_MOCK_INVALIDATION_H_