[CRD iOS] Move UI stuff into a subdirectory

remoting/client/ui/fling_tracker.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_FLING_TRACKER_H_
-#define REMOTING_CLIENT_FLING_TRACKER_H_
+#ifndef REMOTING_CLIENT_UI_FLING_TRACKER_H_
+#define REMOTING_CLIENT_UI_FLING_TRACKER_H_
 
 #include "base/time/time.h"
 
 namespace remoting {
 
 // A class for tracking the positions of an object moving through a viscous
 // liquid.
 class FlingTracker {
  public:
   // time_constant: The larger the number the longer it takes to fling.
@@ skipping 25 matching lines @@
   float previous_position_y_ = 0.f;
 
   base::TimeTicks start_time_;
 
   // FlingTracker is neither copyable nor movable.
   FlingTracker(const FlingTracker&) = delete;
   FlingTracker& operator=(const FlingTracker&) = delete;
 };
 
 }  // namespace remoting
-#endif  // REMOTING_CLIENT_FLING_TRACKER_H_
+#endif  // REMOTING_CLIENT_UI_FLING_TRACKER_H_