[Sync] Clean up ModelType code.

components/sync/base/model_type.h

Index: components/sync/base/model_type.h
diff --git a/components/sync/base/model_type.h b/components/sync/base/model_type.h
index 6525c6a2169114f37ca284ec488709d855f73be1..d8d929cddc1b772651940cbd7231f2b294a9f7cb 100644
--- a/components/sync/base/model_type.h
+++ b/components/sync/base/model_type.h
@@ -91,13 +91,13 @@ enum ModelType {
   EXTENSION_SETTINGS,
   // App notifications.
   APP_NOTIFICATIONS,  // Deprecated.
-  // History delete directives.
+                      // History delete directives.

[pavely, 2017/02/23 23:23:03]

Seems like git cl format messed up indentation.

[skym, 2017/02/24 18:59:07]

It does. I've moved the Deprecated text onto the lines above to avoid this.

   HISTORY_DELETE_DIRECTIVES,
   // Synced push notifications.
   SYNCED_NOTIFICATIONS,  // Deprecated.
-  // Synced Notification app info.
+                         // Synced Notification app info.
   SYNCED_NOTIFICATION_APP_INFO,  // Deprecated.
-  // Custom spelling dictionary.
+                                 // Custom spelling dictionary.
   DICTIONARY,
   // Favicon images.
   FAVICON_IMAGES,
@@ -161,6 +161,9 @@ enum ModelType {
   // histograms for sync include your new type.  In this case, be sure to also
   // update the UserSelectableTypes() definition in
   // sync/syncable/model_type.cc.
+
+  // Additionally, enum SyncModelTypes and suffix SyncModelType need to be
+  // updated in histograms.xml for all new types.
   MODEL_TYPE_COUNT,
 };
 
@@ -175,9 +178,8 @@ inline ModelType ModelTypeFromInt(int i) {
   return static_cast<ModelType>(i);
 }
 
-// Used by tests outside of sync/.
-void AddDefaultFieldValue(ModelType datatype,
-                          sync_pb::EntitySpecifics* specifics);
+// Used to mark the type of EntitySpecifics that has no actual data.
+void AddDefaultFieldValue(ModelType type, sync_pb::EntitySpecifics* specifics);
 
 // Extract the model type of a SyncEntity protocol buffer.  ModelType is a
 // local concept: the enum is not in the protocol.  The SyncEntity's ModelType