[Media Router] Clean up issues related code.

chrome/browser/ui/toolbar/media_router_action.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_UI_TOOLBAR_MEDIA_ROUTER_ACTION_H_
 #define CHROME_BROWSER_UI_TOOLBAR_MEDIA_ROUTER_ACTION_H_
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/media/router/issues_observer.h"
@@ skipping 80 matching lines @@
   // Checks if the current icon of MediaRouterAction has changed. If so,
   // updates |current_icon_|.
   void MaybeUpdateIcon();
 
   gfx::VectorIconId GetCurrentIcon() const;
 
   // The current icon to show. This is updated based on the current issues and
   // routes since |this| is an IssueObserver and MediaRoutesObserver.
   gfx::VectorIconId current_icon_;
 
-  // The current issue shown in the Media Router WebUI. Can be null. It is set
-  // in OnIssueUpdated(), which is called by the IssueManager.
-  std::unique_ptr<media_router::Issue> issue_;
+  // Whether the Media Router UI is currently showing an issue. If |true|,
+  // |current_issue_severity_| indicates the severity of the issue.
+  // Set in OnIssueUpdated(), which is called by the IssueManager.
+  bool has_issue_;

[mark a. foltz, 2016/07/27 18:52:04]

It seems more straightforward for MediaRouterAction to have a
base::Optional<Issue> with a copy of the current issue.

[imcheng, 2016/09/13 20:27:54]

I think the issue (no pun intended) here is that MRA doesn't need to know the
entirety of the issue - just the issue severity is sufficient to determine the
state of the icon. We would also have to implement copy construction which we
are trying to eliminate.

We can make it base::Optional<Severity> to get rid of the |has_issue_| though.

+
+  // The severity of the current issue shown in the Media Router WebUI.
+  // The value is valid only if |has_issue_| is true.
+  // Set in OnIssueUpdated(), which is called by the IssueManager.
+  media_router::Issue::Severity current_issue_severity_;
 
   // Whether a local displayable active route exists.
   bool has_local_display_route_;
 
   ToolbarActionViewDelegate* delegate_;
 
   Browser* const browser_;
   ToolbarActionsBar* const toolbar_actions_bar_;
 
   // The delegate to handle platform-specific implementations.
   std::unique_ptr<MediaRouterActionPlatformDelegate> platform_delegate_;
 
   MediaRouterContextualMenu contextual_menu_;
 
   ScopedObserver<TabStripModel, TabStripModelObserver>
       tab_strip_model_observer_;
 
   base::WeakPtrFactory<MediaRouterAction> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterAction);
 };
 
 #endif  // CHROME_BROWSER_UI_TOOLBAR_MEDIA_ROUTER_ACTION_H_