Add wallpaper experimental api framework and add a simple category list.

chrome/browser/extensions/extension_function_registry.cc

Index: chrome/browser/extensions/extension_function_registry.cc
diff --git a/chrome/browser/extensions/extension_function_registry.cc b/chrome/browser/extensions/extension_function_registry.cc
index 9a38f82768a741201a6c4b96f9ce62ce54990caa..72d484cfe08cdbefc2076189f6ace11e8f99a00b 100644
--- a/chrome/browser/extensions/extension_function_registry.cc
+++ b/chrome/browser/extensions/extension_function_registry.cc
@@ -62,6 +62,7 @@
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/extensions/file_browser_private_api.h"
 #include "chrome/browser/chromeos/extensions/echo_private_api.h"
+#include "chrome/browser/chromeos/extensions/wallpaper_manager_api.h"
 #include "chrome/browser/chromeos/media/media_player_extension_api.h"
 #include "chrome/browser/extensions/api/terminal/terminal_private_api.h"
 #include "chrome/browser/extensions/extension_info_private_api_chromeos.h"
@@ -371,6 +372,9 @@ void ExtensionFunctionRegistry::ResetFunctions() {
   RegisterFunction<SetWindowHeightMediaplayerFunction>();
   RegisterFunction<CloseWindowMediaplayerFunction>();
 
+  // WallpaperManagerPrivate functions.
+  RegisterFunction<WallpaperManagerStringsFunction>();
+
   // InputMethod
   RegisterFunction<GetInputMethodFunction>();