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

chrome/browser/ui/webui/sync_internals_ui.cc

Index: chrome/browser/ui/webui/sync_internals_ui.cc
===================================================================
--- chrome/browser/ui/webui/sync_internals_ui.cc	(revision 117388)
+++ chrome/browser/ui/webui/sync_internals_ui.cc	(working copy)
@@ -73,7 +73,7 @@
 }  // namespace
 
 SyncInternalsUI::SyncInternalsUI(WebContents* contents)
-    : WebUI(contents),
+    : WebUI(contents, this),
       weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
   // TODO(akalin): Fix.
   Profile* profile = Profile::FromBrowserContext(contents->GetBrowserContext());
@@ -94,9 +94,9 @@
   }
 }
 
-void SyncInternalsUI::OnWebUISend(const GURL& source_url,
-                                  const std::string& name,
-                                  const ListValue& content) {
+bool SyncInternalsUI::OverrideHandleWebUIMessage(const GURL& source_url,
+                                                 const std::string& name,
+                                                 const ListValue& content) {
   scoped_ptr<ListValue> content_copy(content.DeepCopy());
   JsArgList args(content_copy.get());
   VLOG(1) << "Received message: " << name << " with args "
@@ -122,6 +122,7 @@
                    << " with args " << args.ToString();
     }
   }
+  return true;
 }
 
 void SyncInternalsUI::HandleJsEvent(