Add support for pinning platform apps

ash/launcher/launcher_model.cc

Index: ash/launcher/launcher_model.cc
diff --git a/ash/launcher/launcher_model.cc b/ash/launcher/launcher_model.cc
index 67d51e44edca110c305ec9f0919013e8a58ca5fa..50625fa516dd2ea99f226daa1c249de0af6771b7 100644
--- a/ash/launcher/launcher_model.cc
+++ b/ash/launcher/launcher_model.cc
@@ -93,9 +93,15 @@ void LauncherModel::Set(int index, const LauncherItem& item) {
   LauncherItem old_item(items_[index]);
   items_[index] = item;
   items_[index].id = old_item.id;
-  items_[index].type = old_item.type;
   FOR_EACH_OBSERVER(LauncherModelObserver, observers_,
                     LauncherItemChanged(index, old_item));
+
+  // If the type changes confirm that the item is still in the right order.
+  if (items_[index].type != old_item.type) {
+    int new_index = ValidateInsertionIndex(items_[index].type, index);

[sky, 2012/06/13 21:20:53]

By updating the item then validating you've broken the ordering. I don't think
ValidateInsertionIndex will behave reliably in this situation.

[DaveMoore, 2012/06/13 22:30:16]

Done.

+    if (new_index != index)
+      Move(index, new_index);
+  }
 }
 
 int LauncherModel::ItemIndexByID(LauncherID id) {