Clean up async app launcher enabled checks.

apps/app_launcher.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef APPS_APP_LAUNCHER_H_
 #define APPS_APP_LAUNCHER_H_
 
 #include "base/callback_forward.h"
 
 namespace apps {
 
-// Called on the UI thread after determining if the launcher is enabled. A
-// boolean flag is passed, which is true if the app launcher is enabled.
-typedef base::Callback<void(bool)> OnAppLauncherEnabledCompleted;
-
-// TODO(calamity): Remove all the "uncertain" apis because windows app launcher
-// enabled is now just a single pref that we can check synchronously and with
-// confidence. This includes changing GetIsAppLauncherEnabled to a synchronous
-// API.
-
-// A synchronous check to determine if the app launcher is enabled. If the
-// registry needs to be determined to find an accurate answer, this function
-// will NOT do so; instead if will default to false (the app launcher is not
-// enabled).
-// This function does not use the cached preference of whether the launcher
-// was enabled or not.
-bool MaybeIsAppLauncherEnabled();
-
-// Determine whether the app launcher is enabled or not. This may involve a trip
-// to a blocking thread. |completion_callback| is called when an answer is
-// ready. This needs to be called on the UI thread.
-void GetIsAppLauncherEnabled(
-    const OnAppLauncherEnabledCompleted& completion_callback);
-
-// Returns whether the app launcher was enabled the last time it was checked.
-bool WasAppLauncherEnabled();
+// Returns whether the app launcher has been enabled.
+bool IsAppLauncherEnabled();
 
 }  // namespace apps
 
 #endif  // APPS_APP_LAUNCHER_H_