mandoline: Make sure omnibox gets updated when navigating back/forwards.

components/web_view/public/interfaces/web_view.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module web_view.mojom;
 
 import "components/mus/public/interfaces/view_tree.mojom";
 import "network/public/interfaces/url_loader.mojom";
 
 enum ButtonState {
   ENABLED,
   DISABLED,
 };
 
 interface WebViewClient {
   // Page-generated request for a top level frame navigation.
-  TopLevelNavigate(mojo.URLRequest request);
+  TopLevelNavigateRequest(mojo.URLRequest request);
+
+  // Notification that the navigation has started. This can be useful for
+  // navigations triggered from sources other than the page itself (e.g.
+  // back/forward history navigation).
+  TopLevelNavigationStarted(string url);
 
   // Loading and progress notifications.
   LoadingStateChanged(bool is_loading, double progress);
   BackForwardChanged(ButtonState back_button, ButtonState forward_button);
 
   // TODO(beng): also forward text direction.
   TitleChanged(string? title);
 };
 
 interface WebView {
   // Navigate the top level frame to |request|.
   LoadRequest(mojo.URLRequest request);
 
   // Provide a ViewTreeClient for this specific WebView.
   GetViewTreeClient(mojo.ViewTreeClient& view_tree_client);
 
   // Moves forward and backward.
   GoBack();
   GoForward();
 };
 
 interface WebViewFactory {
   CreateWebView(WebViewClient client, WebView& web_view);
 };