Remove AboutToNavigateRenderFrame, issue custom notification for DevTools.

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index ec3dd50746f54871fd3ee21036323a4d78d3edb6..7cd453bc96472cefa07739e6c2dcfc863a76e97a 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -610,6 +610,14 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // frames, it will return the current frame's view.
   RenderWidgetHostViewBase* GetViewForAccessibility();
 
+  // Sends a navigate message to the RenderFrame and notifies DevTools about
+  // navigation happening. Should be used instead of sending the message
+  // directly.
+  void SendNavigateMessage(
+      const content::CommonNavigationParams& common_params,
+      const content::StartNavigationParams& start_params,
+      const content::RequestNavigationParams& request_params);
+
   // For now, RenderFrameHosts indirectly keep RenderViewHosts alive via a
   // refcount that calls Shutdown when it reaches zero.  This allows each
   // RenderFrameHostManager to just care about RenderFrameHosts, while ensuring