Move out DidStartProvisionalLoad from WebContentsImpl into Navigator.

content/browser/renderer_host/render_view_host_delegate.h

Index: content/browser/renderer_host/render_view_host_delegate.h
diff --git a/content/browser/renderer_host/render_view_host_delegate.h b/content/browser/renderer_host/render_view_host_delegate.h
index c02954d22f3118e6d1a63b0906dfba760670aaed..a32665b86919c204776cf782965b50cfd52cb889 100644
--- a/content/browser/renderer_host/render_view_host_delegate.h
+++ b/content/browser/renderer_host/render_view_host_delegate.h
@@ -151,14 +151,6 @@ class CONTENT_EXPORT RenderViewHostDelegate {
   // RenderView is going to be destroyed
   virtual void RenderViewDeleted(RenderViewHost* render_view_host) {}
 
-  // The RenderView started a provisional load for a given frame.
-  virtual void DidStartProvisionalLoadForFrame(
-      RenderViewHost* render_view_host,
-      int64 frame_id,
-      int64 parent_frame_id,
-      bool main_frame,
-      const GURL& url) {}
-
   // The RenderView processed a redirect during a provisional load.
   //
   // TODO(creis): Remove this method and have the pre-rendering code listen to