Implement MediaCaptureDevices.

content/public/browser/media_capture_devices.h

Index: content/public/browser/media_capture_devices.h
diff --git a/content/public/browser/media_capture_devices.h b/content/public/browser/media_capture_devices.h
new file mode 100644
index 0000000000000000000000000000000000000000..925fff66c25163756ba535496cdfdf35286128f2
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+++ b/content/public/browser/media_capture_devices.h
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+// 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.
+
+#ifndef CONTENT_PUBLIC_BROWSER_MEDIA_CAPTURE_DEVICES_H_
+#define CONTENT_PUBLIC_BROWSER_MEDIA_CAPTURE_DEVICES_H_
+
+#include "content/public/common/media_stream_request.h"
+
+namespace content {
+
+// This is a singleton class, used to get Audio/Video devices, it must be
+// called in UI thread.
+class CONTENT_EXPORT  MediaCaptureDevices {
+ public:
+  // Get signleton instance of MediaCaptureDevices.
+  static MediaCaptureDevices* GetInstance();
+
+  // Return all Audio/Video devices.
+  virtual const MediaStreamDevices& GetAudioCaptureDevices() = 0;
+  virtual const MediaStreamDevices& GetVideoCaptureDevices() = 0;
+
+ private:
+  // This interface should only be implemented inside content.
+  friend class MediaCaptureDevicesImpl;
+  MediaCaptureDevices() {}
+  virtual ~MediaCaptureDevices() {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_MEDIA_CAPTURE_DEVICES_H_