Add new files for VideoSourceBase to roll into Chrome in preparation for implementatin.

TBR=pthatcher@webrtc.org
BUG=webrtc:5426

Review URL: https://codereview.webrtc.org/1794483003 .

Cr-Commit-Position: refs/heads/master@{#11959}

webrtc/media/base/videosourcebase.cc

@@ -0,0 +1,13 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/media/base/videosourcebase.h"
+
+// TODO(perkj): Add implementation.

webrtc/media/base/videosourcebase.h

@@ -0,0 +1,16 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MEDIA_BASE_VIDEOSOURCEBASE_H_
+#define WEBRTC_MEDIA_BASE_VIDEOSOURCEBASE_H_
+
+// TODO(perkj): Add implementation.
+
+#endif  // WEBRTC_MEDIA_BASE_VIDEOSOURCEBASE_H_

webrtc/media/media.gyp

@@ -74,6 +74,8 @@
         'base/videoframefactory.cc',
         'base/videoframefactory.h',
         'base/videorenderer.h',
+        'base/videosourcebase.cc',
+        'base/videosourcebase.h',
         'base/yuvframegenerator.cc',
         'base/yuvframegenerator.h',
         'devices/deviceinfo.h',