[eme] Handle multiple calls to MediaKeySession.close()

media/blink/webcontentdecryptionmodulesession_impl.cc

 // 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.
 
 #include "webcontentdecryptionmodulesession_impl.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 417 matching lines @@
   }
 
   adapter_->UpdateSession(
       session_id_, sanitized_response,
       std::unique_ptr<SimpleCdmPromise>(new CdmResultPromise<>(
           result, adapter_->GetKeySystemUMAPrefix() + kUpdateSessionUMAName)));
 }
 
 void WebContentDecryptionModuleSessionImpl::close(
     blink::WebContentDecryptionModuleResult result) {
-  // close() shouldn't be called if the session is already closed. blink
-  // prevents a second call to close(), but since the operation is
-  // asynchronous, there is a window where close() was called just before
-  // the closed event arrives. The CDM should handle the case where
-  // close() is called after it has already closed the session.
   DCHECK(!session_id_.empty());
-  DCHECK(!has_close_been_called_);
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  // close() shouldn't be called if the session is already closed. Since the
+  // operation is asynchronous, there is a window where close() was called
+  // just before the closed event arrives. The CDM should handle the case where
+  // close() is called after it has already closed the session. However, if
+  // we can tell the session is now closed, simply resolve the promise.
+  if (is_closed_) {
+    result.complete();
+    return;
+  }
+
   has_close_been_called_ = true;
   adapter_->CloseSession(
       session_id_,
       std::unique_ptr<SimpleCdmPromise>(new CdmResultPromise<>(
           result, adapter_->GetKeySystemUMAPrefix() + kCloseSessionUMAName)));
 }
 
 void WebContentDecryptionModuleSessionImpl::remove(
     blink::WebContentDecryptionModuleResult result) {
   DCHECK(!session_id_.empty());
@@ skipping 60 matching lines @@
 
   DCHECK(session_id_.empty()) << "Session ID may not be changed once set.";
   session_id_ = session_id;
   *status =
       adapter_->RegisterSession(session_id_, weak_ptr_factory_.GetWeakPtr())
           ? SessionInitStatus::NEW_SESSION
           : SessionInitStatus::SESSION_ALREADY_EXISTS;
 }
 
 }  // namespace media