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

chrome/browser/media/router/issue_manager_unittest.cc

Index: chrome/browser/media/router/issue_manager_unittest.cc
diff --git a/chrome/browser/media/router/issue_manager_unittest.cc b/chrome/browser/media/router/issue_manager_unittest.cc
index a331ccb8942ffe3544026b1253aba7010e143a3a..351cce680e3a2f981782a5f8eaed9d79fdb08d73 100644
--- a/chrome/browser/media/router/issue_manager_unittest.cc
+++ b/chrome/browser/media/router/issue_manager_unittest.cc
@@ -17,7 +17,7 @@ const char kTestRouteId[] = "routeId";
 Issue CreateTestIssue(const std::string& route_id) {
   return Issue("title", "message", IssueAction(IssueAction::TYPE_DISMISS),
                std::vector<IssueAction>(), route_id, Issue::WARNING, false,
-               "http://www.example.com/help");
+               12345);
 }
 
 class IssueManagerUnitTest : public ::testing::Test {