Added flag in chrome://flags to enable the New Launcher UI.

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 89f621e2238eedc118e6a1186443c68223e8fa98..8d7123f5fccc43f1bbbd0518d7b8e0af87772a69 100644
--- a/ui/app_list/app_list_switches.cc
+++ b/ui/app_list/app_list_switches.cc
@@ -21,6 +21,9 @@ const char kDisableAppListDismissOnBlur[] = "disable-app-list-dismiss-on-blur";
 // If set, the app list will be enabled as if enabled from CWS.
 const char kEnableAppList[] = "enable-app-list";
 
+// If set, fullscreen app list will be enabled as if the feature flag was set.
+const char kEnableFullscreenAppList[] = "enable-fullscreen-app-list";
+
 // Enable/disable syncing of the app list independent of extensions.
 const char kEnableSyncAppList[] = "enable-sync-app-list";
 const char kDisableSyncAppList[] = "disable-sync-app-list";
@@ -41,6 +44,11 @@ bool IsAppListSyncEnabled() {
       kDisableSyncAppList);
 }
 
+bool IsFullscreenAppListEnabled() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      kEnableFullscreenAppList);
+}
+
 bool IsFolderUIEnabled() {
   // Folder UI is available only when AppList sync is enabled, and should
   // not be disabled separately.