Remove RenderViewHost parameter from WebContentsObserver::Did{Start|Stop}Loading.

chrome/browser/prerender/prerender_contents.cc

Index: chrome/browser/prerender/prerender_contents.cc
diff --git a/chrome/browser/prerender/prerender_contents.cc b/chrome/browser/prerender/prerender_contents.cc
index 4795fa6e83647ee5525899748d0a406c9fca5be0..2ea6a66052183a85c5ee287ec09276c48dbeaced 100644
--- a/chrome/browser/prerender/prerender_contents.cc
+++ b/chrome/browser/prerender/prerender_contents.cc
@@ -545,8 +545,7 @@ void PrerenderContents::RenderFrameCreated(
       render_frame_host->GetRoutingID(), true));
 }
 
-void PrerenderContents::DidStopLoading(
-    content::RenderViewHost* render_view_host) {
+void PrerenderContents::DidStopLoading() {
   has_stopped_loading_ = true;
   NotifyPrerenderStopLoading();
 }