Verify EME calls made on same thread

media/blink/webcontentdecryptionmodulesession_impl.h

 // Copyright 2013 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 MEDIA_BLINK_WEBCONTENTDECRYPTIONMODULESESSION_IMPL_H_
 #define MEDIA_BLINK_WEBCONTENTDECRYPTIONMODULESESSION_IMPL_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "media/base/media_keys.h"
 #include "third_party/WebKit/public/platform/WebContentDecryptionModuleSession.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 
 namespace media {
 
 class CdmSessionAdapter;
 class MediaKeys;
 
 class WebContentDecryptionModuleSessionImpl
@@ skipping 42 matching lines @@
   // Session ID is the app visible ID for this session generated by the CDM.
   // This value is not set until the CDM resolves the initializeNewSession()
   // promise.
   std::string session_id_;
 
   // Don't pass more than 1 close() event to blink::
   // TODO(jrummell): Remove this once blink tests handle close() promise and
   // closed() event.
   bool is_closed_;
 
+  base::ThreadChecker thread_checker_;
   // Since promises will live until they are fired, use a weak reference when
   // creating a promise in case this class disappears before the promise
   // actually fires.
   base::WeakPtrFactory<WebContentDecryptionModuleSessionImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentDecryptionModuleSessionImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBCONTENTDECRYPTIONMODULESESSION_IMPL_H_