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..d63b824340ca396cbb0c90de51f3afb1a56d1d38 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
@@ -198,6 +198,21 @@ SupervisedUserSharedSettingsService::MergeDataAndStartSyncing(
   sync_processor_ = std::move(sync_processor);
   error_handler_ = std::move(error_handler);
 
+  int num_added = 0;
+  int num_modified = 0;
+  int num_before_association = 0;
+  std::map<std::string, std::set<std::string> > pref_seen_keys;
+  const DictionaryValue* pref_dict =
+      prefs_->GetDictionary(prefs::kSupervisedUserSharedSettings);
+  for (DictionaryValue::Iterator it(*pref_dict); !it.IsAtEnd(); it.Advance()) {
+    const DictionaryValue* dict = NULL;

[Bernhard Bauer, 2016/01/07 10:04:29]

Use nullptr instead of NULL.

[Deepak, 2016/01/07 10:40:07]

Done.

+    bool success = it.value().GetAsDictionary(&dict);
+    DCHECK(success);
+    num_before_association += dict->size();
+    for (DictionaryValue::Iterator jt(*dict); !jt.IsAtEnd(); jt.Advance())
+      pref_seen_keys[it.key()].insert(jt.key());
+  }
+
   // 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;

[Bernhard Bauer, 2016/01/07 10:04:29]

Rename this to |sync_seen_keys| to distinguish it from |pref_seen_keys|?

[Deepak, 2016/01/07 10:40:07]

Done.

@@ -224,6 +239,11 @@ SupervisedUserSharedSettingsService::MergeDataAndStartSyncing(
         kAcknowledged, supervised_user_shared_setting.acknowledged());
     callbacks_.Notify(su_id, key);
 
+    if (pref_seen_keys.find(su_id) == pref_seen_keys.end())
+      num_added++;
+    else
+      num_modified++;
+
     seen_keys[su_id].insert(key);
   }
 
@@ -259,7 +279,10 @@ 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);
+  result.set_num_items_before_association(num_before_association);
+  result.set_num_items_after_association(num_before_association + num_added);

[Bernhard Bauer, 2016/01/07 10:04:29]

Let's not do this, please. If we have a bug in the code above, manually counting
the number of items afterwards might expose it, whereas if we calculate it like
this, we don't get anything from verifying that num_after_association ==
num_before_association + num_added.

We already have a loop over the preferences after association (starting at line
255), so we can do the count there.

[Deepak, 2016/01/07 10:40:07]

I got your point. Thanks

   return result;
 }