Upstream the Media Router's Issue class.

chrome/browser/media/router/issues_observer.h

+// 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_ISSUES_OBSERVER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_ISSUES_OBSERVER_H_
+
+#include "chrome/browser/media/router/issue.h"
+
+namespace media_router {
+
+// Interface for observing when issues have been updated.
+// TODO(imcheng): Implement automatic register/unregister from MediaRouter.
+class IssuesObserver {
+ public:
+  virtual ~IssuesObserver() {}
+
+  // Called when there is a new highest priority issue.
+  // |issue| can be nullptr.
+  virtual void OnIssueUpdated(const Issue* issue) = 0;
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_ISSUES_OBSERVER_H_