Chrome OS OOBE: Refactor initialization in oobe_ui.

This CL splits CreateOobeUIDataSource into several smaller functions.

Bug: 864686
Change-Id: I6843595bf66a9584778fa5ebbff8167a0ce605d2
Reviewed-on: https://chromium-review.googlesource.com/1182608
Commit-Queue: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584930}

chrome/browser/ui/webui/chromeos/login/oobe_ui.h

@@ -78,13 +78,14 @@ class OobeUI : public content::WebUIController,
  public:
   // List of known types of OobeUI. Type added as path in chrome://oobe url, for
   // example chrome://oobe/user-adding.
-  static const char kOobeDisplay[];
-  static const char kLoginDisplay[];
-  static const char kLockDisplay[];
-  static const char kUserAddingDisplay[];
   static const char kAppLaunchSplashDisplay[];
   static const char kArcKioskSplashDisplay[];
+  static const char kDiscoverDisplay[];
   static const char kGaiaSigninDisplay[];
+  static const char kLockDisplay[];
+  static const char kLoginDisplay[];
+  static const char kOobeDisplay[];
+  static const char kUserAddingDisplay[];
 
   class Observer {
    public: