mandoline: Add back/forward support and UI.

components/web_view/web_view_impl.h

Index: components/web_view/web_view_impl.h
diff --git a/components/web_view/web_view_impl.h b/components/web_view/web_view_impl.h
index c10a7bef87877f894c0704eabfe54bb89584b6ab..532bc1bc3ab73a228c829b7965495a0e6b5e6ff0 100644
--- a/components/web_view/web_view_impl.h
+++ b/components/web_view/web_view_impl.h
@@ -7,6 +7,7 @@
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
 #include "components/view_manager/public/cpp/view_observer.h"
 #include "components/view_manager/public/cpp/view_tree_delegate.h"
 #include "components/web_view/frame_devtools_agent_delegate.h"
@@ -24,6 +25,7 @@ class Frame;
 class FrameTree;
 class FrameDevToolsAgent;
 class HTMLMessageEvent;
+class NavigationEntry;
 class PendingWebViewLoad;
 
 class WebViewImpl : public mojom::WebView,
@@ -43,11 +45,15 @@ class WebViewImpl : public mojom::WebView,
   // See description above |pending_load_| for details.
   void OnLoad();
 
+  void UpdateBackForwardEnableState();
+
   // Overridden from WebView:
   void LoadRequest(mojo::URLRequestPtr request) override;
   void GetViewTreeClient(
       mojo::InterfaceRequest<mojo::ViewTreeClient> view_tree_client)
           override;
+  void GoBack() override;
+  void GoForward() override;
 
   // Overridden from mojo::ViewTreeDelegate:
   void OnEmbed(mojo::View* root) override;
@@ -89,6 +95,15 @@ class WebViewImpl : public mojom::WebView,
 
   scoped_ptr<FrameDevToolsAgent> devtools_agent_;
 
+  // It would be nice if mojo::URLRequest were cloneable; however, its use of
+  // ScopedDataPipieConsumerHandle means that it isn't.
+  ScopedVector<NavigationEntry> back_list_;

[msw, 2015/09/04 22:05:00]

nit: |backward_list_| to match |forward_list_|

+  ScopedVector<NavigationEntry> forward_list_;

[msw, 2015/09/04 22:05:00]

Consider having a single list and an iterator for the current element.
(that should make going back/forward cleaner; no juggling list entries)

+
+  // The request which is either currently loading or completed loading. On a

[msw, 2015/09/04 22:05:00]

nit: consider "The current request, which may be loading or completed."

+  // new navigation where this

[msw, 2015/09/04 22:05:00]

Incomplete sentence

+  scoped_ptr<NavigationEntry> current_page_request_;

[msw, 2015/09/04 22:05:00]

nit: consider |current_request_|

+
   DISALLOW_COPY_AND_ASSIGN(WebViewImpl);
 };