Use ChromeLauncherControllerImpl::GetItem; cleanup.

ash/common/shelf/shelf_model.cc

Index: ash/common/shelf/shelf_model.cc
diff --git a/ash/common/shelf/shelf_model.cc b/ash/common/shelf/shelf_model.cc
index 04705e42bba10079bad171eca6d54d0ad960a08c..273d5ac9c815ebe1d95878c00b744b19e69be939 100644
--- a/ash/common/shelf/shelf_model.cc
+++ b/ash/common/shelf/shelf_model.cc
@@ -91,6 +91,9 @@ void ShelfModel::Move(int index, int target_index) {
 
 void ShelfModel::Set(int index, const ShelfItem& item) {
   DCHECK(index >= 0 && index < item_count());
+  if (index < 0 || index >= item_count())

[James Cook, 2016/12/06 05:54:22]

Yeah, this is all that I meant.

optional: You could also remove the DCHECK line and put a NOTREACHED inside the
if().

[msw, 2016/12/06 18:02:22]

Done.

+    return;
+
   int new_index = item.type == items_[index].type
                       ? index
                       : ValidateInsertionIndex(item.type, index);