Add Statistics for SupervisedUserSettingService during merging and syncing data.

chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.cc

Index: chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.cc
diff --git a/chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.cc b/chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.cc
index 60ec741691a6160e6fb02412b393bfb035aeac18..38e54f25dc0db1f72cab85bcc5d5b864b7c2b417 100644
--- a/chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.cc
+++ b/chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.cc
@@ -201,7 +201,8 @@ SupervisedUserSharedSettingsService::MergeDataAndStartSyncing(
   // We keep a map from MU ID to the set of keys that we have seen in the
   // initial sync data.
   std::map<std::string, std::set<std::string> > seen_keys;
-
+  int num_added = 0;
+  int num_modified = 0;
   // Iterate over all initial sync data, and update it locally. This means that
   // the value from the server always wins over a local value.
   for (const SyncData& sync_data : initial_sync_data) {
@@ -224,6 +225,10 @@ SupervisedUserSharedSettingsService::MergeDataAndStartSyncing(
         kAcknowledged, supervised_user_shared_setting.acknowledged());
     callbacks_.Notify(su_id, key);
 
+    if (seen_keys.find(su_id) == seen_keys.end())
+      num_added++;
+    else
+      num_modified++;
     seen_keys[su_id].insert(key);
   }
 
@@ -259,7 +264,8 @@ SupervisedUserSharedSettingsService::MergeDataAndStartSyncing(
         sync_processor_->ProcessSyncChanges(FROM_HERE, change_list));
   }
 
-  // TODO(bauerb): Statistics?
+  result.set_num_items_added(num_added);
+  result.set_num_items_modified(num_modified);

[Bernhard Bauer, 2016/01/05 14:10:54]

Add the number of items before and after association as well?

(And I would actually not do anything clever like inferring the number of items
afterwards from the number of items beforehand plus the number of added items,
because the correctness of that is what we want to verify.)

[Deepak, 2016/01/06 05:26:30]

Done.

   return result;
 }