Upstream iOS web code.

ios/web/public/web_state/web_state_observer.h

Index: ios/web/public/web_state/web_state_observer.h
diff --git a/ios/web/public/web_state/web_state_observer.h b/ios/web/public/web_state/web_state_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..78bc2b2fb065a42e84abb353fe504757665b169e
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+++ b/ios/web/public/web_state/web_state_observer.h
@@ -0,0 +1,71 @@
+// Copyright 2014 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_PUBLIC_WEB_STATE_WEB_STATE_OBSERVER_H_
+#define IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_OBSERVER_H_
+
+#include "base/macros.h"
+
+namespace ios {
+class WebState;
+}
+
+namespace web {
+
+struct LoadCommittedDetails;
+
+class WebStateObserver {

[stuartmorgan, 2014/12/04 23:22:58]

Whoops :( Could you add a class-level comment while you're here?

+ public:
+  // Returns the web state associated with this observer.
+  ios::WebState* web_state() const { return web_state_; }
+
+  // This method is invoked when a new non-pending navigation item is created.
+  // This corresponds to one NavigationManager item being created
+  // (in the case of new navigations) or renavigated to (for back/forward
+  // navigations).
+  virtual void NavigationItemCommitted(
+      const LoadCommittedDetails& load_details) {};
+
+  // Called when the current page is loaded.
+  virtual void PageLoaded() {};
+
+  // Called on URL hash change events.
+  virtual void URLHashChanged() {};
+
+  // Called on history state change events.
+  virtual void HistoryStateChanged() {};
+
+  // Invoked when the WebState is being destroyed. Gives subclasses a chance
+  // to cleanup.
+  virtual void WebStateDestroyed() {}
+
+ protected:
+  // Use this constructor when the object is tied to a single WebState for
+  // its entire lifetime.
+  explicit WebStateObserver(ios::WebState* web_state);
+
+  // Use this constructor when the object wants to observe a WebState for
+  // part of its lifetime.  It can then call Observe() to start and stop
+  // observing.
+  WebStateObserver();
+
+  virtual ~WebStateObserver();
+
+  // Start observing a different WebState; used with the default constructor.
+  void Observe(ios::WebState* web_state);
+
+ private:
+  friend class WebStateImpl;

[stuartmorgan, 2014/12/04 23:22:58]

Shouldn't there be a forward declaration for this class?

+
+  // Stops observing the current web state.
+  void ResetWebState();
+
+  ios::WebState* web_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebStateObserver);
+};
+
+}  // namespace web
+
+#endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_