Make launching apps from shelf more intuitive

chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.cc

Index: chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.cc
diff --git a/chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.cc b/chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.cc
index f1bf9036b90887e6e41ce79cb3189479deff466e..1019a95e13f2ade812560d3aa90bb88bd03fdd86 100644
--- a/chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.cc
+++ b/chrome/browser/ui/ash/launcher/app_shortcut_launcher_item_controller.cc
@@ -8,6 +8,8 @@
 
 #include <utility>
 
+#include "ash/root_window_controller.h"
+#include "ash/shell.h"
 #include "ash/wm/window_util.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/extensions/launch_util.h"
@@ -114,10 +116,15 @@ void AppShortcutLauncherItemController::ItemSelected(
       return;
     }
 
+    aura::Window* root_window =
+        ash::Shell::Get()
+            ->GetRootWindowControllerWithDisplayId(display_id)
+            ->GetRootWindow();
+
     // Launching some items replaces this item controller instance, which
     // destroys its ShelfID string pair; making copies avoid crashes.
-    ChromeLauncherController::instance()->LaunchApp(ash::ShelfID(shelf_id()),
-                                                    source, ui::EF_NONE);
+    ChromeLauncherController::instance()->LaunchApp(
+        ash::ShelfID(shelf_id()), source, ui::EF_NONE, root_window);
     std::move(callback).Run(ash::SHELF_ACTION_NEW_WINDOW_CREATED,
                             base::nullopt);
     return;