EME: Close existing sessions on CDM failure

media/base/cdm_session_tracker.cc

Index: media/base/cdm_session_tracker.cc
diff --git a/media/base/cdm_session_tracker.cc b/media/base/cdm_session_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..437581fc4db030a9b49112e65db795a55282cabc
--- /dev/null
+++ b/media/base/cdm_session_tracker.cc
@@ -0,0 +1,35 @@
+// 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.
+
+#include "media/base/cdm_session_tracker.h"
+
+namespace media {
+
+CdmSessionTracker::CdmSessionTracker() {}
+
+CdmSessionTracker::~CdmSessionTracker() {
+  DCHECK(session_ids_.empty());
+}
+
+void CdmSessionTracker::AddSession(const std::string& session_id) {
+  DCHECK(session_ids_.find(session_id) == session_ids_.end());
+  session_ids_.insert(session_id);
+}
+
+void CdmSessionTracker::RemoveSession(const std::string& session_id) {
+  auto it = session_ids_.find(session_id);
+  DCHECK(it != session_ids_.end());
+  session_ids_.erase(it);
+}
+
+void CdmSessionTracker::CloseRemainingSessions(
+    SessionClosedCB session_closed_cb) {
+  std::unordered_set<std::string> session_ids;
+  session_ids.swap(session_ids_);
+
+  for (const auto& session_id : session_ids)
+    session_closed_cb.Run(session_id);
+}
+
+}  // namespace media