EME: Close existing sessions on CDM failure

media/base/cdm_session_tracker.h

Index: media/base/cdm_session_tracker.h
diff --git a/media/base/cdm_session_tracker.h b/media/base/cdm_session_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..c72e25c72b40508438885f3e26e47fa5e0b9e305
--- /dev/null
+++ b/media/base/cdm_session_tracker.h
@@ -0,0 +1,43 @@
+// Copyright 2016 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_BASE_CDM_SESSION_TRACKER_H_
+#define MEDIA_BASE_CDM_SESSION_TRACKER_H_
+
+#include <stdint.h>
+
+#include <string>
+#include <unordered_set>
+
+#include "base/logging.h"
+#include "base/macros.h"
+#include "media/base/media_export.h"
+#include "media/base/media_keys.h"
+
+namespace media {
+
+class MEDIA_EXPORT CdmSessionTracker {
+ public:
+  CdmSessionTracker();
+  ~CdmSessionTracker();
+
+  // Add |session_id| to the list of sessions being tracked.
+  void AddSession(const std::string& session_id);
+
+  // Remove |session_id| from the list of sessions being tracked.
+  void RemoveSession(const std::string& session_id);
+
+  // Call |session_closed_cb| on any remaining sessions in the list and then
+  // clear the list.
+  void CloseRemainingSessions(const SessionClosedCB& session_closed_cb);
+
+ private:
+  std::unordered_set<std::string> session_ids_;
+
+  DISALLOW_COPY_AND_ASSIGN(CdmSessionTracker);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_CDM_SESSION_TRACKER_H_