Center and change the aspect ratio for the experimental app list. [Win]

ui/app_list/app_list_switches.cc

Index: ui/app_list/app_list_switches.cc
diff --git a/ui/app_list/app_list_switches.cc b/ui/app_list/app_list_switches.cc
index 6c9afb30bc11b77487712aade745718277f4767c..c2cb8730fd0425c02129ac4d99a0041bc88b230e 100644
--- a/ui/app_list/app_list_switches.cc
+++ b/ui/app_list/app_list_switches.cc
@@ -9,6 +9,9 @@
 namespace app_list {
 namespace switches {
 
+// If set, the experimental app list will be used.
+const char kEnableExperimentalAppList[] = "enable-experimental-app-list";
+
 // If set, folder will be enabled in app list UI.
 const char kEnableFolderUI[] = "enable-app-list-folder-ui";