media: CdmFactory creates CDM (MediaKeys) asynchronously.

media/cdm/default_cdm_factory.cc

 // 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 "media/cdm/default_cdm_factory.h"
 
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop_proxy.h"
 #include "media/base/key_systems.h"
 #include "media/cdm/aes_decryptor.h"
 #include "url/gurl.h"
 
 namespace media {
 
 DefaultCdmFactory::DefaultCdmFactory() {
 }
 
 DefaultCdmFactory::~DefaultCdmFactory() {
 }
 
-scoped_ptr<MediaKeys> DefaultCdmFactory::Create(
+void DefaultCdmFactory::Create(
     const std::string& key_system,
     bool allow_distinctive_identifier,
     bool allow_persistent_state,
     const GURL& security_origin,
     const SessionMessageCB& session_message_cb,
     const SessionClosedCB& session_closed_cb,
     const LegacySessionErrorCB& legacy_session_error_cb,
     const SessionKeysChangeCB& session_keys_change_cb,
-    const SessionExpirationUpdateCB& session_expiration_update_cb) {
-  if (!security_origin.is_valid())
-    return nullptr;
-
-  if (CanUseAesDecryptor(key_system)) {
-    return make_scoped_ptr(new AesDecryptor(security_origin, session_message_cb,
-                                            session_closed_cb,
-                                            session_keys_change_cb));
+    const SessionExpirationUpdateCB& session_expiration_update_cb,
+    const CdmCreatedCB& cdm_created_cb) {
+  if (!security_origin.is_valid() || !CanUseAesDecryptor(key_system)) {
+    base::MessageLoopProxy::current()->PostTask(
+        FROM_HERE, base::Bind(cdm_created_cb, nullptr));
+    return;
   }
 
-  return nullptr;
+  scoped_ptr<MediaKeys> cdm(
+      new AesDecryptor(security_origin, session_message_cb, session_closed_cb,
+                       session_keys_change_cb));
+  base::MessageLoopProxy::current()->PostTask(
+      FROM_HERE, base::Bind(cdm_created_cb, base::Passed(&cdm)));
 }
 
 }  // namespace media