Extension settings API: send ACTION_UPDATE rather than ACTION_ADD when a

chrome/browser/extensions/extension_settings_sync_unittest.cc

 // Copyright (c) 2011 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 "testing/gtest/include/gtest/gtest.h"
 
 #include "base/bind.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 208 matching lines @@
   ASSERT_PRED_FORMAT2(ValuesEq, &value2, &all_sync_data["s2"][0].value());
 
   SyncDataList sync_data;
   sync_data.push_back(extension_settings_sync_util::CreateData(
       "s1", "foo", value1));
   sync_data.push_back(extension_settings_sync_util::CreateData(
       "s2", "bar", value2));
 
   backend_->MergeDataAndStartSyncing(
       syncable::EXTENSION_SETTINGS, sync_data, &sync_);
-  backend_->StopSyncing(syncable::EXTENSION_SETTINGS);
 
   // Already in sync, so no changes.
   ASSERT_EQ(0u, sync_.changes().size());
+
+  // Regression test: not-changing the synced value shouldn't result in a sync
+  // change, and changing the synced value should result in an update.
+  storage1->Set("foo", value1);
+  ASSERT_EQ(0u, sync_.changes().size());
+
+  storage1->Set("foo", value2);
+  ASSERT_EQ(1u, sync_.changes().size());
+  ExtensionSettingSyncData change = sync_.GetOnlyChange("s1", "foo");
+  ASSERT_EQ(SyncChange::ACTION_UPDATE, change.change_type());
+  ASSERT_TRUE(value2.Equals(&change.value()));
+
+  backend_->StopSyncing(syncable::EXTENSION_SETTINGS);
 }
 
 TEST_F(ExtensionSettingsSyncTest, LocalDataWithNoSyncDataIsPushedToSync) {
   StringValue value1("fooValue");
   ListValue value2;
   value2.Append(StringValue::CreateStringValue("barValue"));
 
   SyncableExtensionSettingsStorage* storage1 = GetStorage("s1");
   SyncableExtensionSettingsStorage* storage2 = GetStorage("s2");
 
@@ skipping 247 matching lines @@
       sync_.GetOnlyChange("s3", "bar").change_type());
   ASSERT_EQ(
       SyncChange::ACTION_DELETE,
       sync_.GetOnlyChange("s4", "foo").change_type());
   ASSERT_EQ(
       SyncChange::ACTION_DELETE,
       sync_.GetOnlyChange("s4", "bar").change_type());
 
   backend_->StopSyncing(syncable::EXTENSION_SETTINGS);
 }