Add UMA to track app launcher discoverability.

chrome/common/pref_names.h

 // Copyright (c) 2012 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.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 
 #include <stddef.h>
@@ skipping 889 matching lines @@
 
 #if defined(ENABLE_APP_LIST)
 extern const char kAppListProfile[];
 extern const char kRestartWithAppList[];
 
 extern const char kLastAppListLaunchPing[];
 extern const char kAppListLaunchCount[];
 extern const char kLastAppListAppLaunchPing[];
 extern const char kAppListAppLaunchCount[];
 extern const char kAppLauncherHasBeenEnabled[];
+extern const char kAppListEnableMethod[];
+extern const char kAppListEnableTime[];
 extern const char kAppLauncherIsEnabled[];
 extern const char kAppLauncherShortcutVersion[];
 extern const char kShowAppLauncherPromo[];
 #endif
 
 extern const char kAppLaunchForMetroRestart[];
 extern const char kAppLaunchForMetroRestartProfile[];
 extern const char kAppShortcutsHaveBeenCreated[];
 
 extern const char kModuleConflictBubbleShown[];
@@ skipping 16 matching lines @@
 #if defined(OS_WIN)
 extern const char kOsPasswordBlank[];
 extern const char kOsPasswordLastChanged[];
 #endif
 
 extern const char kQuickCheckEnabled[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_