Refactor ModelTypePayloadMap and ObjectIdPayloadMap to StateMaps.

sync/internal_api/public/base/model_type_state_map.h

Index: sync/internal_api/public/base/model_type_state_map.h
diff --git a/sync/internal_api/public/base/model_type_state_map.h b/sync/internal_api/public/base/model_type_state_map.h
new file mode 100644
index 0000000000000000000000000000000000000000..e9c5592e96a93ff2168b8fe952579591e6cdad80
--- /dev/null
+++ b/sync/internal_api/public/base/model_type_state_map.h
@@ -0,0 +1,60 @@
+// Copyright (c) 2012 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.
+//
+// Definition of ModelTypeStateMap and various utility functions.
+
+#ifndef SYNC_INTERNAL_PUBLIC_API_BASE_MODEL_TYPE_STATE_MAP_H_
+#define SYNC_INTERNAL_PUBLIC_API_BASE_MODEL_TYPE_STATE_MAP_H_
+
+#include <map>
+#include <string>
+
+#include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/model_type.h"
+
+// TODO(akalin): Move the non-exported functions in this file to a
+// private header.
+
+namespace base {
+class DictionaryValue;
+}
+
+namespace syncer {
+
+struct InvalidationState {

[akalin, 2012/08/13 19:41:48]

can we move this into its own header?  I think it'll end up being big enough to
warrant its own header

[dcheng, 2012/08/18 00:41:29]

Done.

+  std::string payload;
+  std::string ack_handle;

[akalin, 2012/08/13 19:41:48]

can we use invalidation::AckHandle for now, until we figure out how we want to
do our own AckHandles?  I'm a big wary of using plain strings for ack handles...

[dcheng, 2012/08/18 00:41:29]

I've just declared an empty AckHandle class for now in invalidation_state.h.
Reusing invalidation::AckHandle causes a lot of complications with #includes.

+
+  bool operator==(const InvalidationState& rhs) const;

[akalin, 2012/08/13 19:41:48]

use Equals()

[dcheng, 2012/08/18 00:41:29]

As discussed, we are now using Gmock matchers.

+};
+
+// A container that contains a set of datatypes with possible string
+// payloads.
+typedef std::map<ModelType, InvalidationState> ModelTypeStateMap;
+
+// Helper functions for building ModelTypeStateMaps.
+
+// Make a TypeStateMap from all the types in a ModelTypeSet using a
+// default payload.
+SYNC_EXPORT ModelTypeStateMap ModelTypeStateMapFromEnumSet(
+    ModelTypeSet model_types, const std::string& payload);
+
+ModelTypeSet ModelTypeStateMapToEnumSet(
+    const ModelTypeStateMap& payload_map);
+
+std::string ModelTypeStateMapToString(
+    const ModelTypeStateMap& model_type_payloads);
+
+// Caller takes ownership of the returned dictionary.
+base::DictionaryValue* ModelTypeStateMapToValue(
+    const ModelTypeStateMap& model_type_payloads);
+
+// Coalesce |update| into |original|, overwriting only when |update| has
+// a non-empty payload.
+void CoalesceStates(ModelTypeStateMap* original,
+                    const ModelTypeStateMap& update);
+
+}  // namespace syncer
+
+#endif  // SYNC_INTERNAL_PUBLIC_API_BASE_MODEL_TYPE_STATE_MAP_H_