Remove --show-app-list-shortcut flag and implement new app launcher enable logic.

apps/pref_names.cc

Index: apps/pref_names.cc
diff --git a/apps/pref_names.cc b/apps/pref_names.cc
index cb1cf937e7e4bffc492c11e97cc0a7574bf5bb69..b4d3176a594112a72114f76b23587bff3b327b81 100644
--- a/apps/pref_names.cc
+++ b/apps/pref_names.cc
@@ -8,10 +8,6 @@ namespace apps {
 
 namespace prefs {
 
-// Local state caching knowledge of whether the app launcher is installed.
-const char kAppLauncherIsEnabled[] =
-    "apps.app_launcher.should_show_apps_page";
-
 // If set, the user requested to launch the app with this extension id while
 // in Metro mode, and then relaunched to Desktop mode to start it.
 const char kAppLaunchForMetroRestart[] = "apps.app_launch_for_metro_restart";
@@ -21,6 +17,16 @@ const char kAppLaunchForMetroRestart[] = "apps.app_launch_for_metro_restart";
 const char kAppLaunchForMetroRestartProfile[] =
     "apps.app_launch_for_metro_restart_profile";
 
+// A boolean that tracks whether the user has ever enabled the app launcher.
+const char kAppLauncherHasBeenEnabled[] =
+    "apps.app_launcher.has_been_enabled";
+
+// TODO(calamity): remove this pref since app launcher will always be
+// installed.
+// Local state caching knowledge of whether the app launcher is installed.
+const char kAppLauncherIsEnabled[] =
+    "apps.app_launcher.should_show_apps_page";
+
 // A boolean identifying if we should show the app launcher promo or not.
 const char kShowAppLauncherPromo[] = "app_launcher.show_promo";