[Media Router] Clean up issues related code.

chrome/browser/ui/toolbar/media_router_action.h

Index: chrome/browser/ui/toolbar/media_router_action.h
diff --git a/chrome/browser/ui/toolbar/media_router_action.h b/chrome/browser/ui/toolbar/media_router_action.h
index ace06a32f18e0cdfe7f86ea861e907c9cdadf917..ac7592c1429ec29de427980532f365f15333cc0d 100644
--- a/chrome/browser/ui/toolbar/media_router_action.h
+++ b/chrome/browser/ui/toolbar/media_router_action.h
@@ -98,9 +98,15 @@ class MediaRouterAction : public ToolbarActionViewController,
   // 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_;