[Media Router] Clean up issues related code.

chrome/browser/media/router/issues_observer.h

Index: chrome/browser/media/router/issues_observer.h
diff --git a/chrome/browser/media/router/issues_observer.h b/chrome/browser/media/router/issues_observer.h
index 87534916be5f3ce5b684612c8bcd70dc7a1343f9..5a8467cdfd1dd41d11f27e2d41d3190b6ba00d97 100644
--- a/chrome/browser/media/router/issues_observer.h
+++ b/chrome/browser/media/router/issues_observer.h
@@ -19,8 +19,9 @@ class IssuesObserver {
   explicit IssuesObserver(MediaRouter* router);
   virtual ~IssuesObserver();
 
-  void RegisterObserver();
-  void UnregisterObserver();
+  // Registers with Media Router to start observing for Issues. No-ops if Init()
+  // has already been called before.
+  void Init();
 
   // Called when there is an updated Media Router Issue.
   // If |issue| is nullptr, then there is currently no issue.
@@ -28,6 +29,7 @@ class IssuesObserver {
 
  private:
   MediaRouter* router_;
+  bool initialized_;
 
   DISALLOW_COPY_AND_ASSIGN(IssuesObserver);
 };