ash: Change auto to not deduce raw pointers.

ash/shelf/shelf_layout_manager_unittest.cc

Index: ash/shelf/shelf_layout_manager_unittest.cc
diff --git a/ash/shelf/shelf_layout_manager_unittest.cc b/ash/shelf/shelf_layout_manager_unittest.cc
index 13a37937f4c80d9994a2e27b3e2e56f918a429e5..4cc2dd11e29734d26c249df06447069d6188602a 100644
--- a/ash/shelf/shelf_layout_manager_unittest.cc
+++ b/ash/shelf/shelf_layout_manager_unittest.cc
@@ -1154,7 +1154,7 @@ TEST_F(ShelfLayoutManagerTest, DimmingBehaviorDualDisplay) {
   EXPECT_EQ(root_windows.size(), 2U);
 
   std::vector<ShelfWidget*> shelf_widgets;
-  for (auto& root_window : root_windows) {
+  for (auto* root_window : root_windows) {
     ShelfLayoutManager* shelf =
         GetRootWindowController(root_window)->GetShelfLayoutManager();
     shelf_widgets.push_back(shelf->shelf_widget());