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 8ee8ed8c79d0a4335836612b0d932179606331b9..d3e04f48a3d4439b47ebf4822b55f6b167b0e51d 100644
--- a/chrome/browser/prerender/prerender_contents.cc
+++ b/chrome/browser/prerender/prerender_contents.cc
@@ -588,8 +588,7 @@ void PrerenderContents::RenderFrameCreated(
       render_frame_host->GetRoutingID(), true));
 }
 
-void PrerenderContents::DidStopLoading(
-    content::RenderViewHost* render_view_host) {
+void PrerenderContents::DidStopLoading() {
   has_stopped_loading_ = true;
   NotifyPrerenderStopLoading();
 }