[Media Router] Consistently refer to issue's learn more help page by ID.

chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc

Index: chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
diff --git a/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc b/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
index c7ebce4fa3eea2fb73b86396a4a8e55acd46d648..1883829493543ec4ef81db654eb88c1aff8ab3dd 100644
--- a/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
+++ b/chrome/browser/ui/webui/media_router/media_router_webui_message_handler.cc
@@ -210,6 +210,8 @@ std::unique_ptr<base::DictionaryValue> IssueToValue(const Issue& issue) {
   if (!issue.route_id().empty())
     dictionary->SetString("routeId", issue.route_id());
   dictionary->SetBoolean("isBlocking", issue.is_blocking());
+  if (issue.help_page_id() > 0)
+    dictionary->SetInteger("helpPageId", issue.help_page_id());
 
   return dictionary;
 }
@@ -467,7 +469,7 @@ void MediaRouterWebUIMessageHandler::OnCreateRoute(
         l10n_util::GetStringUTF8(IDS_MEDIA_ROUTER_ISSUE_PENDING_ROUTE),
         std::string(), IssueAction(IssueAction::TYPE_DISMISS),
         std::vector<IssueAction>(), std::string(), Issue::NOTIFICATION,
-        false, std::string());
+        false, -1);
     media_router_ui_->AddIssue(issue);
     return;
   }
@@ -560,7 +562,7 @@ void MediaRouterWebUIMessageHandler::OnJoinRoute(const base::ListValue* args) {
         l10n_util::GetStringUTF8(IDS_MEDIA_ROUTER_ISSUE_PENDING_ROUTE),
         std::string(), IssueAction(IssueAction::TYPE_DISMISS),
         std::vector<IssueAction>(), std::string(), Issue::NOTIFICATION,
-        false, std::string());
+        false, -1);
     media_router_ui_->AddIssue(issue);
     return;
   }