Verify EME calls made on same thread

media/base/cdm_promise_adapter.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/base/cdm_promise_adapter.h"
 
 #include "media/base/media_keys.h"
 
 namespace media {
 
 CdmPromiseAdapter::CdmPromiseAdapter() : next_promise_id_(1) {
 }
 
 CdmPromiseAdapter::~CdmPromiseAdapter() {
   DCHECK(promises_.empty());
+  DCHECK(thread_checker_.CalledOnValidThread());
   Clear();
 }
 
 uint32_t CdmPromiseAdapter::SavePromise(scoped_ptr<CdmPromise> promise) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   uint32_t promise_id = next_promise_id_++;
   promises_.add(promise_id, promise.Pass());
   return promise_id;
 }
 
 template <typename... T>
 void CdmPromiseAdapter::ResolvePromise(uint32_t promise_id,
                                        const T&... result) {
   scoped_ptr<CdmPromise> promise = TakePromise(promise_id);
   if (!promise) {
@@ skipping 20 matching lines @@
   if (!promise) {
     NOTREACHED() << "No promise found for promise_id " << promise_id;
     return;
   }
 
   promise->reject(exception_code, system_code, error_message);
 }
 
 void CdmPromiseAdapter::Clear() {
   // Reject all outstanding promises.
+  DCHECK(thread_checker_.CalledOnValidThread());
   for (auto& promise : promises_)
     promise.second->reject(MediaKeys::UNKNOWN_ERROR, 0, "Operation aborted.");
   promises_.clear();
 }
 
 scoped_ptr<CdmPromise> CdmPromiseAdapter::TakePromise(uint32_t promise_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   PromiseMap::iterator it = promises_.find(promise_id);
   if (it == promises_.end())
     return nullptr;
   return promises_.take_and_erase(it);
 }
 
 // Explicit instantiation of function templates.
 template MEDIA_EXPORT void CdmPromiseAdapter::ResolvePromise(uint32_t);
 template MEDIA_EXPORT void CdmPromiseAdapter::ResolvePromise(
     uint32_t,
     const std::string&);
 
 }  // namespace media