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

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index 0cc85e0a47842f2e18d189c055f2efc519718e10..a176d18cbb06363238243250980f44e7083962b3 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -244,8 +244,8 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
 
   // These two methods correspond to the points in time when the spinner of the
   // tab starts and stops spinning.
-  virtual void DidStartLoading(RenderViewHost* render_view_host) {}
-  virtual void DidStopLoading(RenderViewHost* render_view_host) {}
+  virtual void DidStartLoading() {}
+  virtual void DidStopLoading() {}
 
   // When WebContents::Stop() is called, the WebContents stops loading and then
   // invokes this method. If there are ongoing navigations, their respective