Add DesktopFrame rotation functions

webrtc/modules/desktop_capture/desktop_frame_rotation.h

Index: webrtc/modules/desktop_capture/desktop_frame_rotation.h
diff --git a/webrtc/modules/desktop_capture/desktop_frame_rotation.h b/webrtc/modules/desktop_capture/desktop_frame_rotation.h
new file mode 100644
index 0000000000000000000000000000000000000000..6dc0a9eda70cad423be7e254f922cbecb2ccc9bc
--- /dev/null
+++ b/webrtc/modules/desktop_capture/desktop_frame_rotation.h
@@ -0,0 +1,44 @@
+/*
+ *  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_MODULES_DESKTOP_CAPTURE_DESKTOP_FRAME_ROTATION_H_
+#define WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_FRAME_ROTATION_H_
+
+#include "webrtc/modules/desktop_capture/desktop_frame.h"
+#include "webrtc/modules/desktop_capture/desktop_geometry.h"
+
+namespace webrtc {
+
+// Represents the rotation of a DesktopFrame.
+enum class Rotation {
+  CLOCK_WISE_0,
+  CLOCK_WISE_90,
+  CLOCK_WISE_180,
+  CLOCK_WISE_270,
+};
+
+// Rotates input DesktopFrame |source|, copies pixel in a rotated rectangle
+// |rect| into another DesktopFrame |target|, and adds |rect| into
+// |target|->mutable_updated_region().
+// |rotation| specifies |source| to |target| rotation. |rect| is in |target|
+// coordinate.
+// This function triggers check failure if |target| does not cover the |rect|.
+void RotateDesktopFrame(const DesktopFrame& source,
+                        const Rotation& rotation,
+                        const DesktopRect& rect,
+                        DesktopFrame* target);
+
+// Returns a rotated DesktopRect of |rect|. The |size| represents the size of
+// the DesktopFrame which |rect| belongs in.
+DesktopRect RotateRect(DesktopRect rect, DesktopSize size, Rotation rotation);
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_FRAME_ROTATION_H_