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

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 c1e05026b1f152e69fcea4f547bec8359b0e8287..cda09b84c2f5e8a73d68a4a1a425fd854c8d5b39 100644
--- a/ui/app_list/app_list_switches.cc
+++ b/ui/app_list/app_list_switches.cc
@@ -25,16 +25,20 @@ const char kEnableExperimentalAppList[] = "enable-experimental-app-list";
 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
 }