Convert tests to use the non-deprecated WebContentsObserver navigation methods.

content/browser/web_contents/web_contents_impl_browsertest.cc

Index: content/browser/web_contents/web_contents_impl_browsertest.cc
diff --git a/content/browser/web_contents/web_contents_impl_browsertest.cc b/content/browser/web_contents/web_contents_impl_browsertest.cc
index 976b7fc74120b689ad5b42e8cff4a9b5c7a31ea5..6a6dae67a935098692bf8134a76f4b2e0f68f75d 100644
--- a/content/browser/web_contents/web_contents_impl_browsertest.cc
+++ b/content/browser/web_contents/web_contents_impl_browsertest.cc
@@ -158,9 +158,7 @@ class RenderViewSizeObserver : public WebContentsObserver {
     rwhv_create_size_ = rvh->GetWidget()->GetView()->GetViewBounds().size();
   }
 
-  void DidStartProvisionalLoadForFrame(RenderFrameHost* render_frame_host,
-                                       const GURL& url,
-                                       bool is_error_page) override {
+  void DidStartNavigation(NavigationHandle* navigation_handle) override {
     ResizeWebContentsView(shell_, wcv_new_size_, false);
   }