[Part-2]Add Statistics for SupervisedUserSettingService during merging and syncing data.

chrome/browser/supervised_user/supervised_user_settings_service_unittest.cc

Index: chrome/browser/supervised_user/supervised_user_settings_service_unittest.cc
diff --git a/chrome/browser/supervised_user/supervised_user_settings_service_unittest.cc b/chrome/browser/supervised_user/supervised_user_settings_service_unittest.cc
index c3c8836a304c3bf0c567c9f55e95f1e216050dc8..e76742f3cc590b64e24136b530d57ecbc09fdd8c 100644
--- a/chrome/browser/supervised_user/supervised_user_settings_service_unittest.cc
+++ b/chrome/browser/supervised_user/supervised_user_settings_service_unittest.cc
@@ -70,13 +70,15 @@ class SupervisedUserSettingsServiceTest : public ::testing::Test {
         new syncer::SyncChangeProcessorWrapperForTest(sync_processor_.get()));
   }
 
-  void StartSyncing(const syncer::SyncDataList& initial_sync_data) {
+  syncer::SyncMergeResult StartSyncing(
+      const syncer::SyncDataList& initial_sync_data) {
     scoped_ptr<syncer::SyncErrorFactory> error_handler(
         new MockSyncErrorFactory(syncer::SUPERVISED_USER_SETTINGS));
     syncer::SyncMergeResult result = settings_service_.MergeDataAndStartSyncing(
         syncer::SUPERVISED_USER_SETTINGS, initial_sync_data,
         CreateSyncProcessor(), std::move(error_handler));
     EXPECT_FALSE(result.error().IsSet());
+    return result;
   }
 
   void UploadSplitItem(const std::string& key, const std::string& value) {
@@ -202,6 +204,60 @@ TEST_F(SupervisedUserSettingsServiceTest, ProcessSplitSetting) {
   EXPECT_TRUE(dict_value->Equals(&dict));
 }
 
+TEST_F(SupervisedUserSettingsServiceTest, Merge) {
+  syncer::SyncMergeResult result = StartSyncing(syncer::SyncDataList());
+  EXPECT_EQ(0, result.num_items_added());
+  EXPECT_EQ(0, result.num_items_deleted());
+  EXPECT_EQ(0, result.num_items_modified());
+  EXPECT_EQ(0, result.num_items_before_association());
+  EXPECT_EQ(0, result.num_items_after_association());
+
+  ASSERT_TRUE(settings_);
+  const base::Value* value = NULL;

[Bernhard Bauer, 2016/01/08 16:04:46]

nullptr please.

[Deepak, 2016/01/11 10:38:36]

Done.

+  EXPECT_FALSE(settings_->GetWithoutPathExpansion(kSettingsName, &value));
+
+  base::DictionaryValue dict;
+  dict.SetString("foo", "bar");
+  dict.SetBoolean("awesomesauce", true);
+  dict.SetInteger("eaudecologne", 4711);
+
+  settings_.reset();
+  syncer::SyncDataList sync_data;
+  sync_data.push_back(SupervisedUserSettingsService::CreateSyncDataForSetting(
+      kSettingsName, base::StringValue(kSettingsValue)));
+  for (base::DictionaryValue::Iterator it(dict); !it.IsAtEnd(); it.Advance()) {
+    sync_data.push_back(SupervisedUserSettingsService::CreateSyncDataForSetting(
+        SupervisedUserSettingsService::MakeSplitSettingKey(kSettingsName,
+                                                           it.key()),
+        it.value()));
+  }
+
+  result = StartSyncing(sync_data);
+  EXPECT_EQ(4, result.num_items_added());

[Bernhard Bauer, 2016/01/08 16:04:46]

This is somewhat strange. Why do we add four items? I only see three entries in
the dictionary.

[Deepak, 2016/01/11 10:38:36]

I am adding a entry in sync_data at line 226.
and 3 entry in the sync_data via dictionary. 
So sync_data have total 4 entries.

[Bernhard Bauer, 2016/01/18 17:56:56]

Oh, right. Could you add a comment that explains that we add the three
dictionary entries and this atomic entry?

+  EXPECT_EQ(0, result.num_items_deleted());
+  EXPECT_EQ(0, result.num_items_modified());
+  EXPECT_EQ(0, result.num_items_before_association());
+  EXPECT_EQ(4, result.num_items_after_association());
+
+  sync_data.clear();
+  dict.Clear();
+  dict.SetString("foo", "burp");
+  dict.SetString("item", "first");
+  for (base::DictionaryValue::Iterator it(dict); !it.IsAtEnd(); it.Advance()) {
+    sync_data.push_back(SupervisedUserSettingsService::CreateSyncDataForSetting(
+        SupervisedUserSettingsService::MakeSplitSettingKey(kSettingsName,

[Bernhard Bauer, 2016/01/08 16:04:46]

This only uses split settings. It would be good to also exercise the code for
some atomic settings and queued items.

[Deepak, 2016/01/11 10:38:36]

Done.

+                                                           it.key()),
+        it.value()));
+  }
+
+  result = StartSyncing(sync_data);
+  EXPECT_EQ(1, result.num_items_added());
+  EXPECT_EQ(3, result.num_items_deleted());
+  EXPECT_EQ(1, result.num_items_modified());
+  EXPECT_EQ(4, result.num_items_before_association());
+  EXPECT_EQ(2, result.num_items_after_association());
+}
+
 TEST_F(SupervisedUserSettingsServiceTest, SetLocalSetting) {
   const base::Value* value = NULL;
   EXPECT_FALSE(settings_->GetWithoutPathExpansion(kSettingsName, &value));