Move code that doesn't depend on PPAPI out of remoting/client/plugin

remoting/client/normalizing_input_filter_cros.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
+// Copyright 2015 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.
 
-#include "remoting/protocol/input_filter.h"
+#ifndef REMOTING_CLIENT_NORMALIZING_INPUT_FILTER_CROS_H_
+#define REMOTING_CLIENT_NORMALIZING_INPUT_FILTER_CROS_H_
 
 #include "remoting/proto/event.pb.h"
+#include "remoting/protocol/input_filter.h"
 
 namespace remoting {
 
 // NormalizingInputFilterCros addresses the problems generated by key rewritings
 // such as Down->PageDown, 1->F1, etc, when keys are pressed in combination with
 // the OSKey (aka Search). Rewriting OSKey+Down, for example, causes us to
 // receive the following:
 //
 // keydown OSKey
 // keydown PageDown
@@ skipping 34 matching lines @@
   bool left_alt_is_pressed_;
 
   // Previous mouse coordinates.
   int previous_mouse_x_;
   int previous_mouse_y_;
 
   DISALLOW_COPY_AND_ASSIGN(NormalizingInputFilterCros);
 };
 
 }  // namespace remoting
+
+#endif  // REMOTING_CLIENT_NORMALIZING_INPUT_FILTER_CROS_H_