[CRD iOS] Move UI stuff into a subdirectory

remoting/client/ui/view_matrix.h

 // Copyright 2017 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_CLIENT_VIEW_MATRIX_H_
-#define REMOTING_CLIENT_VIEW_MATRIX_H_
+#ifndef REMOTING_CLIENT_UI_VIEW_MATRIX_H_
+#define REMOTING_CLIENT_UI_VIEW_MATRIX_H_
 
 #include <array>
 
 namespace remoting {
 
 // A 2D non-skew equally scaled transformation matrix.
 // | SCALE, 0,     OFFSET_X, |
 // | 0,     SCALE, OFFSET_Y, |
 // | 0,     0,     1         |
 class ViewMatrix {
@@ skipping 47 matching lines @@
   // Converts to the 3x3 matrix array.
   std::array<float, 9> ToMatrixArray() const;
 
  private:
   float scale_;
   Vector2D offset_;
 };
 
 }  // namespace remoting
 
-#endif  // REMOTING_CLIENT_VIEW_MATRIX_H_
+#endif  // REMOTING_CLIENT_UI_VIEW_MATRIX_H_