[Media Router] Clean up issues related code.

chrome/browser/ui/toolbar/media_router_action.cc

Index: chrome/browser/ui/toolbar/media_router_action.cc
diff --git a/chrome/browser/ui/toolbar/media_router_action.cc b/chrome/browser/ui/toolbar/media_router_action.cc
index d8b04d5622481c5ffedd028c24d64b9e34775a8a..64e0569c062386c1fa5020241767c5ff6b170c09 100644
--- a/chrome/browser/ui/toolbar/media_router_action.cc
+++ b/chrome/browser/ui/toolbar/media_router_action.cc
@@ -54,11 +54,10 @@ MediaRouterAction::MediaRouterAction(Browser* browser,
   DCHECK(toolbar_actions_bar_);
   tab_strip_model_observer_.Add(browser_->tab_strip_model());
   toolbar_actions_bar_observer_.Add(toolbar_actions_bar_);
-  RegisterObserver();
+  IssuesObserver::Init();
 }
 
 MediaRouterAction::~MediaRouterAction() {
-  UnregisterObserver();
 }
 
 // static
@@ -166,7 +165,11 @@ bool MediaRouterAction::DisabledClickOpensMenu() const {
 }
 
 void MediaRouterAction::OnIssueUpdated(const media_router::Issue* issue) {
-  issue_.reset(issue ? new media_router::Issue(*issue) : nullptr);
+  if (!issue)
+    current_issue_severity_.reset();
+  else
+    current_issue_severity_ = issue->info().severity;
+
   MaybeUpdateIcon();
 }
 
@@ -266,11 +269,13 @@ void MediaRouterAction::MaybeUpdateIcon() {
 
 gfx::VectorIconId MediaRouterAction::GetCurrentIcon() const {
   // Highest priority is to indicate whether there's an issue.
-  if (issue_) {
-    if (issue_->severity() == media_router::Issue::FATAL)
+  if (current_issue_severity_.has_value()) {
+    if (*current_issue_severity_ == media_router::IssueInfo::Severity::FATAL)
       return gfx::VectorIconId::MEDIA_ROUTER_ERROR;
-    if (issue_->severity() == media_router::Issue::WARNING)
+    else if (*current_issue_severity_ ==
+             media_router::IssueInfo::Severity::WARNING)
       return gfx::VectorIconId::MEDIA_ROUTER_WARNING;
+    // Fall through for Severity::NOTIFICATION.
   }
 
   return has_local_display_route_ ? gfx::VectorIconId::MEDIA_ROUTER_ACTIVE