Disable app list folders by default for non-ChromeOS platforms.

ui/app_list/app_list_switches.cc

 // 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.
 
 #include "ui/app_list/app_list_switches.h"
 
 #include "base/command_line.h"
 
 namespace app_list {
 namespace switches {
 
 // If set, folder will be disabled in app list UI.
 const char kDisableFolderUI[] = "disable-app-list-folder-ui";
 
 // If set, the voice search is disabled in app list UI.
 const char kDisableVoiceSearch[] = "disable-app-list-voice-search";
 
 // If set, the app info context menu item is available in the app list UI.
 const char kEnableAppInfo[] = "enable-app-list-app-info";
 
 // If set, the experimental app list will be used.
 const char kEnableExperimentalAppList[] = "enable-experimental-app-list";
 
 // If set, the experimental app list position will be used.
 const char kEnableExperimentalAppListPosition[] =
     "enable-experimental-app-list-position";
 
+// If set, folders will be enabled in the app list UI.
+const char kEnableFolderUI[] = "enable-app-list-folder-ui";
+
 // If set, it will always listen to the audio locally and open the app-list
 // when the hotword is recognized.
 const char kEnableHotwordAlwaysOn[] = "enable-app-list-hotword-always-on";
 
-// Folder UI is enabled by default.
 bool IsFolderUIEnabled() {
-#if !defined(OS_MACOSX)
+#if defined(OS_CHROMEOS)
+  // The folder UI is enabled by default on ChromeOS.
   return !CommandLine::ForCurrentProcess()->HasSwitch(kDisableFolderUI);
 #else
-  return false;
+  // The folder UI is disabled by default for Max, Windows and Linux.
+  return CommandLine::ForCurrentProcess()->HasSwitch(kEnableFolderUI);
 #endif
 }
 
 bool IsVoiceSearchEnabled() {
   // Speech recognition in AppList is only for ChromeOS right now.
 #if defined(OS_CHROMEOS)
   return !CommandLine::ForCurrentProcess()->HasSwitch(kDisableVoiceSearch);
 #else
   return false;
 #endif
@@ skipping 18 matching lines @@
 }
 
 bool IsExperimentalAppListPositionEnabled() {
   return CommandLine::ForCurrentProcess()->HasSwitch(
              kEnableExperimentalAppListPosition) ||
          IsExperimentalAppListEnabled();
 }
 
 }  // namespace switches
 }  // namespace app_list