Add Origin Trials Test interface, rather than attaching trials directly to internals.

third_party/WebKit/Source/core/testing/WorkerInternals.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/testing/WorkerInternals.h"
 
+#include "core/testing/OriginTrialsTest.h"
+
 namespace blink {
 
 // static
 WorkerInternals* WorkerInternals::create(ScriptState* scriptState)
 {
     return new WorkerInternals(scriptState);
 }
 
 WorkerInternals::~WorkerInternals()
 {
 }
 
 WorkerInternals::WorkerInternals(ScriptState*)
 {
 }
 
+OriginTrialsTest* WorkerInternals::originTrialsTest() const
+{
+    return OriginTrialsTest::create();
+}
+
 } // namespace blink