Implement features needed for local ack handling in InvalidationStateTracker.

sync/internal_api/public/base/invalidation.cc

 // 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.
 
 #include "sync/internal_api/public/base/invalidation.h"
 
+#include <cstddef>
+#include "base/rand_util.h"
+#include "base/string_number_conversions.h"
 #include "base/values.h"
 
 namespace syncer {
 
-bool AckHandle::Equals(const AckHandle& other) const {
-  return true;
+namespace {
+// Hopefully enough bytes for uniqueness.
+const size_t kBytesInHandle = 16;
+// This is not a valid handle name, since all valid handles are 16 bytes long.
+const char kInvalidHandleName[] = "INVALIDHANDLENAME";
+COMPILE_ASSERT(kBytesInHandle != arraysize(kInvalidHandleName),
+               invalid_handle_name_must_differ_in_length_from_valid_handles);
+}  // namespace
+
+AckHandle AckHandle::CreateUnique() {
+  // This isn't a valid UUID, so we don't attempt to format it like one.
+  uint8_t random_bytes[kBytesInHandle];
+  base::RandBytes(random_bytes, sizeof(random_bytes));
+  return AckHandle(base::HexEncode(random_bytes, sizeof(random_bytes)));
 }
 
-scoped_ptr<base::Value> AckHandle::ToValue() const {
-  return scoped_ptr<base::Value>(new DictionaryValue());
+AckHandle AckHandle::InvalidAckHandle() {
+  return AckHandle(kInvalidHandleName);
 }
 
-bool AckHandle::ResetFromValue(const base::Value& value) {
-  return true;
+bool AckHandle::Equals(const AckHandle& other) const {
+  return state_ == other.state_;
+}
+
+scoped_ptr<base::DictionaryValue> AckHandle::ToValue() const {
+  scoped_ptr<DictionaryValue> value(new DictionaryValue());
+  value->SetString("state", state_);
+  return value.Pass();
+}
+
+bool AckHandle::ResetFromValue(const base::DictionaryValue& value) {
+  return value.GetString("state", &state_);
+}
+
+bool AckHandle::IsValid() const {
+  return state_ != kInvalidHandleName;
+}
+
+AckHandle::AckHandle(const std::string& state) : state_(state) {
+}
+
+Invalidation::Invalidation()
+    : ack_handle(AckHandle::InvalidAckHandle()) {
 }
 
 bool Invalidation::Equals(const Invalidation& other) const {
   return (payload == other.payload) && ack_handle.Equals(other.ack_handle);
 }
 
 scoped_ptr<base::DictionaryValue> Invalidation::ToValue() const {
   scoped_ptr<DictionaryValue> value(new DictionaryValue());
   value->SetString("payload", payload);
   value->Set("ackHandle", ack_handle.ToValue().release());
   return value.Pass();
 }
 
 bool Invalidation::ResetFromValue(const base::DictionaryValue& value) {
-  const base::Value* ack_handle_value = NULL;
+  const DictionaryValue* ack_handle_value = NULL;
   return
       value.GetString("payload", &payload) &&
-      value.Get("ackHandle", &ack_handle_value) &&
+      value.GetDictionary("ackHandle", &ack_handle_value) &&
       ack_handle.ResetFromValue(*ack_handle_value);
 }
 
 }  // namespace syncer