Start splitting out WebUI into an implementation class and an interface that each page implements...

chrome/browser/ui/webui/chromeos/sim_unlock_ui.h

Index: chrome/browser/ui/webui/chromeos/sim_unlock_ui.h
===================================================================
--- chrome/browser/ui/webui/chromeos/sim_unlock_ui.h	(revision 117388)
+++ chrome/browser/ui/webui/chromeos/sim_unlock_ui.h	(working copy)
@@ -7,6 +7,7 @@
 #pragma once
 
 #include "content/browser/webui/web_ui.h"
+#include "content/public/browser/web_ui_controller.h"
 
 namespace chromeos {
 
@@ -14,7 +15,7 @@
 // in Chrome OS for specific tasks:
 // - Unlock SIM card (enter PIN/PUK codes).
 // - Display "SIM card is blocked" message when there're no PUK tries left.
-class SimUnlockUI : public WebUI {
+class SimUnlockUI : public WebUI, public content::WebUIController {
  public:
   explicit SimUnlockUI(content::WebContents* contents);