Have ScriptPromiseResolver on the Oilpan heap always.

Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp

 // Copyright 2014 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 "config.h"
 #include "modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.h"
 
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "core/dom/DOMException.h"
@@ skipping 77 matching lines @@
 
     // EncryptedMediaRequest implementation.
     WebString keySystem() const override { return m_keySystem; }
     const WebVector<WebMediaKeySystemConfiguration>& supportedConfigurations() const override { return m_supportedConfigurations; }
     SecurityOrigin* securityOrigin() const override { return m_resolver->executionContext()->securityOrigin(); }
     void requestSucceeded(WebContentDecryptionModuleAccess*) override;
     void requestNotSupported(const WebString& errorMessage) override;
 
     ScriptPromise promise() { return m_resolver->promise(); }
 
+    DEFINE_INLINE_VIRTUAL_TRACE()
+    {
+        visitor->trace(m_resolver);
+        EncryptedMediaRequest::trace(visitor);
+    }
+
 private:
-    RefPtr<ScriptPromiseResolver> m_resolver;
+    Member<ScriptPromiseResolver> m_resolver;
     const String m_keySystem;
     WebVector<WebMediaKeySystemConfiguration> m_supportedConfigurations;
 };
 
 MediaKeySystemAccessInitializer::MediaKeySystemAccessInitializer(ScriptState* scriptState, const String& keySystem, const HeapVector<MediaKeySystemConfiguration>& supportedConfigurations)
     : m_resolver(ScriptPromiseResolver::create(scriptState))
     , m_keySystem(keySystem)
     , m_supportedConfigurations(supportedConfigurations.size())
 {
     for (size_t i = 0; i < supportedConfigurations.size(); ++i) {
@@ skipping 93 matching lines @@
     //    initialize the MediaKeySystemAccess object.
     MediaKeysController* controller = MediaKeysController::from(document->page());
     WebEncryptedMediaClient* mediaClient = controller->encryptedMediaClient(executionContext);
     mediaClient->requestMediaKeySystemAccess(WebEncryptedMediaRequest(initializer));
 
     // 8. Return promise.
     return promise;
 }
 
 } // namespace blink