Implemented WebStateObserver::DidFinishNavigation(NavigationHandle*).

ios/web/web_state/navigation_handle_impl.h

Index: ios/web/web_state/navigation_handle_impl.h
diff --git a/ios/web/web_state/navigation_handle_impl.h b/ios/web/web_state/navigation_handle_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..6a2aff1df9e6744d902f5dd8b2c6165e240f2028
--- /dev/null
+++ b/ios/web/web_state/navigation_handle_impl.h
@@ -0,0 +1,57 @@
+// Copyright 2017 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.
+
+#ifndef IOS_WEB_WEB_STATE_NAVIGATION_HANDLE_IMPL_H_
+#define IOS_WEB_WEB_STATE_NAVIGATION_HANDLE_IMPL_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "ios/web/public/web_state/navigation_handle.h"
+#include "url/gurl.h"
+
+namespace web {
+
+// Tracks information related to a single navigation.
+class NavigationHandleImpl : public NavigationHandle {
+ public:
+  // Creates navigation handle for sucessful navigation to a different page.
+  static std::unique_ptr<NavigationHandle> CreateNavigationHandle(
+      WebState* web_state,
+      const GURL& url);
+
+  // Creates navigation handle for sucessful same page navigation.
+  static std::unique_ptr<NavigationHandle> CreateSamePageNavigationHandle(
+      WebState* web_state,
+      const GURL& url);
+
+  // Creates navigation handle for the error page navigation.
+  static std::unique_ptr<NavigationHandle> CreateErrorPageNavigationHandle(
+      WebState* web_state,
+      const GURL& url);
+
+  NavigationHandleImpl(WebState* web_state,
+                       const GURL& url,
+                       bool is_same_page,
+                       bool is_error_page);

[kkhorimoto, 2017/02/22 01:42:38]

Do we want to enforce the use of the static factory methods by moving the
constructor to private?

[Eugene But (OOO till 7-30), 2017/02/22 17:54:33]

I've actually tried that but base::MakeUnique needs to call that constructor. I
did not find any Chrome headers with friend declaration of MakeUnique, so doubt
that I can make constructor private and use MakeUnique at the same time. Do you
have any ideas how to fix this without using operator new?

[kkhorimoto, 2017/02/22 18:38:05]

I'm not sure.  I haven't been using MakeUnique to create unique pointers, as it
feels more natural to me to just use the std::unique_ptr() constructor that
takes a pointer created with the "new" keyword.  I did a quick search for C++
objects created using the "new" keyword and found over 5000 in our codebase, so
it doesn't seem like there's much consensus about MakeUnique() clearly being the
best practice.  I'd say that if using "new" helps to refine an object's
interface, as it does here, we should use it instead of MakeUnique.

[Eugene But (OOO till 7-30), 2017/02/22 21:44:56]

Done.

+  ~NavigationHandleImpl() override;
+
+  // NavigationHandle overrides:
+  WebState* GetWebState() override;
+  const GURL& GetUrl() const override;
+  bool IsSamePage() const override;
+  bool IsErrorPage() const override;
+
+ private:
+  WebState* web_state_ = nullptr;
+  GURL url_;
+  bool is_same_page_ = false;
+  bool is_error_page_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_WEB_STATE_NAVIGATION_HANDLE_IMPL_H_