[Media Router] Clean up issues related code.

chrome/browser/media/router/mojo/media_router_type_converters.h

Index: chrome/browser/media/router/mojo/media_router_type_converters.h
diff --git a/chrome/browser/media/router/mojo/media_router_type_converters.h b/chrome/browser/media/router/mojo/media_router_type_converters.h
index 59ad961fd7201814687c636ac4893dfee5f4564c..3581e59ed48330b85e4d60331bf3e46cf9b3167d 100644
--- a/chrome/browser/media/router/mojo/media_router_type_converters.h
+++ b/chrome/browser/media/router/mojo/media_router_type_converters.h
@@ -53,12 +53,6 @@ struct TypeConverter<std::unique_ptr<media_router::MediaRoute>,
 };
 
 // Issue conversion.
-media_router::Issue::Severity IssueSeverityFromMojo(
-    media_router::interfaces::Issue::Severity severity);
-
-media_router::IssueAction::Type IssueActionTypeFromMojo(
-    media_router::interfaces::Issue::ActionType action_type);
-
 template <>
 struct TypeConverter<media_router::Issue, media_router::interfaces::IssuePtr> {
   static media_router::Issue Convert(