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

content/public/test/test_navigation_observer.cc

Index: content/public/test/test_navigation_observer.cc
diff --git a/content/public/test/test_navigation_observer.cc b/content/public/test/test_navigation_observer.cc
index b82bda9a8c34a4be195118aafa3e4e0452918bf9..7c2d0281a59b552e57522f317a001b445940ca53 100644
--- a/content/public/test/test_navigation_observer.cc
+++ b/content/public/test/test_navigation_observer.cc
@@ -38,11 +38,11 @@ class TestNavigationObserver::TestWebContentsObserver
     parent_->OnWebContentsDestroyed(this, web_contents());
   }
 
-  void DidStartLoading(RenderViewHost* render_view_host) override {
+  void DidStartLoading() override {
     parent_->OnDidStartLoading(web_contents());
   }
 
-  void DidStopLoading(RenderViewHost* render_view_host) override {
+  void DidStopLoading() override {
     parent_->OnDidStopLoading(web_contents());
   }