Upstream iOS web code.

ios/web/public/web_state/web_state_observer.h

+// 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 web {
+
+struct LoadCommittedDetails;
+class WebState;
+class WebStateImpl;
+
+// An observer API implemented by classes which are interested in various page
+// load events from WebState.
+class WebStateObserver {
+ public:
+  // Returns the web state associated with this observer.
+  WebState* web_state() const { return web_state_; }

[tfarina, 2014/12/12 18:41:07]

this is not fully const-correctness. Could you make this:

const WebState* web_state() const { ... }

And if necessary add:

WebState* web_state() { ... }

?

This can save trouble later on.

[stuartmorgan, 2014/12/12 19:16:45]

This matches WebContentsObserver's WebContents getter, by design. I don't want
to diverge without a good reason, so if you want to change this please propose a
patch that changes it for both locations and ensure that it works in all the
code using content/

+
+  // 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) {};

[tfarina, 2014/12/12 18:41:07]

no need of ';' in those virtual methods.

[stuartmorgan, 2014/12/12 19:19:57]

If you find style nits in already-submitted code, it's generally much more
useful to just send a patch fixing them than to drive-by nit the CL after the
fact.

+
+  // 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(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(WebState* web_state);
+
+ private:
+  friend class WebStateImpl;
+
+  // Stops observing the current web state.
+  void ResetWebState();
+
+  WebState* web_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebStateObserver);
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_PUBLIC_WEB_STATE_WEB_STATE_OBSERVER_H_