Move Service Worker %2f validation logic from browser into Blink (3)

content/browser/service_worker/service_worker_utils.cc

Index: content/browser/service_worker/service_worker_utils.cc
diff --git a/content/browser/service_worker/service_worker_utils.cc b/content/browser/service_worker/service_worker_utils.cc
index 71ddc611d00d9fd00382bcc119fb819dafca3ba3..8a63857f63c44ad7a3ff10caa7256f359f9fcafb 100644
--- a/content/browser/service_worker/service_worker_utils.cc
+++ b/content/browser/service_worker/service_worker_utils.cc
@@ -94,11 +94,13 @@ bool ServiceWorkerUtils::ContainsDisallowedCharacter(
     std::string* error_message) {
   if (PathContainsDisallowedCharacter(scope) ||
       PathContainsDisallowedCharacter(script_url)) {
-    *error_message = "The provided scope ('";
-    error_message->append(scope.spec());
-    error_message->append("') or scriptURL ('");
-    error_message->append(script_url.spec());
-    error_message->append("') includes a disallowed escape character.");
+    if (error_message) {
+      *error_message = "The provided scope ('";
+      error_message->append(scope.spec());
+      error_message->append("') or scriptURL ('");
+      error_message->append(script_url.spec());
+      error_message->append("') includes a disallowed escape character.");
+    }
     return true;
   }
   return false;