Add DesktopShapeTracker with implementation for Windows

remoting/host/desktop_shape_tracker.h

Index: remoting/host/desktop_shape_tracker.h
diff --git a/remoting/host/desktop_shape_tracker.h b/remoting/host/desktop_shape_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..5abe1f28c00fcb6a44fc791366fc4709e9887123
--- /dev/null
+++ b/remoting/host/desktop_shape_tracker.h
@@ -0,0 +1,38 @@
+// Copyright (c) 2013 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 REMOTING_HOST_DESKTOP_SHAPE_TRACKER_H_
+#define REMOTING_HOST_DESKTOP_SHAPE_TRACKER_H_
+
+#include "base/memory/scoped_ptr.h"
+
+namespace webrtc {
+class DesktopCaptureOptions;
+class DesktopRegion;
+}  // namespace webrtc
+
+namespace remoting {
+
+// Tracks changes in the area of the desktop that is occupied by windows.
+class DesktopShapeTracker {
+ public:
+  static scoped_ptr<DesktopShapeTracker> Create(
+      webrtc::DesktopCaptureOptions options);
+
+  DesktopShapeTracker() {}
+  virtual ~DesktopShapeTracker() {}
+
+  // Recalculates the desktop shape, as returned by desktop_shape();
+  virtual void RefreshDesktopShape() = 0;
+
+  // Returns a reference to the most recently capture desktop shape.
+  virtual const webrtc::DesktopRegion& desktop_shape() = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DesktopShapeTracker);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_DESKTOP_SHAPE_TRACKER_H_