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

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

 // 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.
 
 #ifndef WorkerInternals_h
 #define WorkerInternals_h
 
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/GarbageCollected.h"
 
 namespace blink {
 
+class OriginTrialsTest;
+
 class WorkerInternals final : public GarbageCollectedFinalized<WorkerInternals>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static WorkerInternals* create(ScriptState*);
     virtual ~WorkerInternals();
+    OriginTrialsTest* originTrialsTest() const;
 
     DEFINE_INLINE_TRACE() {}
 private:
     explicit WorkerInternals(ScriptState*);
 };
 
 } // namespace blink
 
 #endif // WorkerInternals_h