Improve SecurityError message on verifyProtocolHandlerScheme()

Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp

Index: Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
diff --git a/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp b/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
index df33faf653a043e35e7e35c781a7440d448ab64e..cf6917a9cd4842bcc2e127dc975a831094d2c61a 100644
--- a/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
+++ b/Source/modules/navigatorcontentutils/NavigatorContentUtils.cpp
@@ -109,13 +109,13 @@ static bool verifyProtocolHandlerScheme(const String& scheme, ExceptionState& es
         // The specification requires that the length of scheme is at least five characteres (including 'web+' prefix).
         if (scheme.length() >= 5 && isValidProtocol(scheme))
             return true;
-        es.throwDOMException(SecurityError);
+        es.throwSecurityError("Failed to verify '" + scheme + "' scheme. '" + scheme + "' is not valid protocol or length isn't at least five characters.");
         return false;
     }
 
     if (isProtocolWhitelisted(scheme))
         return true;
-    es.throwDOMException(SecurityError);
+    es.throwSecurityError("Failed to verify '" + scheme + "' scheme. '" + scheme + "' doesn't belong to the protocol whitelist.");
     return false;
 }