1 files changed, 61 insertions, 0 deletions
diff --git a/dom/media/systemservices/DeviceChangeCallback.h b/dom/media/systemservices/DeviceChangeCallback.h
new file mode 100644
index 000000000..d153e9cd4
--- /dev/null
+++ b/dom/media/systemservices/DeviceChangeCallback.h
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et ft=cpp : */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_DeviceChangeCallback_h
+#define mozilla_DeviceChangeCallback_h
+
+namespace mozilla {
+
+class DeviceChangeCallback
+{
+public:
+  virtual void OnDeviceChange()
+  {
+    MutexAutoLock lock(mCallbackMutex);
+    for (DeviceChangeCallback* observer : mDeviceChangeCallbackList)
+    {
+      observer->OnDeviceChange();
+    }
+  }
+
+  virtual int AddDeviceChangeCallback(DeviceChangeCallback* aCallback)
+  {
+    MutexAutoLock lock(mCallbackMutex);
+    if (mDeviceChangeCallbackList.IndexOf(aCallback) == mDeviceChangeCallbackList.NoIndex)
+      mDeviceChangeCallbackList.AppendElement(aCallback);
+    return 0;
+  }
+
+  virtual int RemoveDeviceChangeCallback(DeviceChangeCallback* aCallback)
+  {
+    MutexAutoLock lock(mCallbackMutex);
+    return RemoveDeviceChangeCallbackLocked(aCallback);
+  }
+
+  virtual int RemoveDeviceChangeCallbackLocked(DeviceChangeCallback* aCallback)
+  {
+    mCallbackMutex.AssertCurrentThreadOwns();
+    if (mDeviceChangeCallbackList.IndexOf(aCallback) != mDeviceChangeCallbackList.NoIndex)
+      mDeviceChangeCallbackList.RemoveElement(aCallback);
+    return 0;
+  }
+
+  DeviceChangeCallback() : mCallbackMutex("mozilla::media::DeviceChangeCallback::mCallbackMutex")
+  {
+  }
+
+  virtual ~DeviceChangeCallback()
+  {
+  }
+
+protected:
+  nsTArray<DeviceChangeCallback*> mDeviceChangeCallbackList;
+  Mutex mCallbackMutex;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_DeviceChangeCallback_h