[Media Router] Clean up issues related code.

chrome/browser/media/router/issue_manager.h

Index: chrome/browser/media/router/issue_manager.h
diff --git a/chrome/browser/media/router/issue_manager.h b/chrome/browser/media/router/issue_manager.h
index 0c9ae27cb64b584a1269f6b997f92c16e60851ca..9c0b8c9d44417a4652dbd19a0ff8c333386c9eaf 100644
--- a/chrome/browser/media/router/issue_manager.h
+++ b/chrome/browser/media/router/issue_manager.h
@@ -59,7 +59,7 @@ class IssueManager {
 
  private:
   // Checks if the current top issue has changed. Updates |top_issue_|.
-  // If |top_issue_| has changed, issues in |issues_observers_| will be
+  // If |top_issue_| has changed, observers in |issues_observers_| will be
   // notified of the new top issue.
   void MaybeUpdateTopIssue();
 
@@ -68,8 +68,8 @@ class IssueManager {
   // IssueObserver insteances are not owned by the manager.
   base::ObserverList<IssuesObserver> issues_observers_;
 
-  // The ID of the current top issue.
-  Issue::Id top_issue_id_;
+  // Pointer to the top Issue in |issues_|, or null if there are no Issues.
+  const Issue* top_issue_;

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

Consider base::Optional<Issue>.

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

Keeping this as a pointer so we don't have to copy construct an extra Issue.

 
   DISALLOW_COPY_AND_ASSIGN(IssueManager);
 };