Move out DidStartProvisionalLoad from WebContentsImpl into Navigator.

content/public/test/test_renderer_host.cc

Index: content/public/test/test_renderer_host.cc
diff --git a/content/public/test/test_renderer_host.cc b/content/public/test/test_renderer_host.cc
index a876c4f2a253cf92daaed2f87cd4661b87686d08..1f9290cd0a90da55f3de26003a01025177fb7829 100644
--- a/content/public/test/test_renderer_host.cc
+++ b/content/public/test/test_renderer_host.cc
@@ -101,6 +101,12 @@ RenderViewHost* RenderViewHostTestHarness::active_rvh() {
   return pending_rvh() ? pending_rvh() : rvh();
 }
 
+RenderFrameHost* RenderViewHostTestHarness::main_rfh() {
+  WebContentsImpl* web_contents = static_cast<WebContentsImpl*>(
+      this->web_contents());
+  return web_contents->GetFrameTree()->GetMainFrame();
+}
+
 BrowserContext* RenderViewHostTestHarness::browser_context() {
   return browser_context_.get();
 }