Remove DisplayStructTraitsTest interface.

ui/display/mojo/display_snapshot_mojo_struct_traits.cc

 // 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.
 
 #include "ui/display/mojo/display_snapshot_mojo_struct_traits.h"
 
-#include "ipc/ipc_message_utils.h"
-#include "ui/display/mojo/display_constants_struct_traits.h"
-#include "ui/display/mojo/display_mode_struct_traits.h"
 #include "ui/display/types/display_constants.h"
-#include "ui/gfx/geometry/mojo/geometry_struct_traits.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace mojo {
 
 namespace {
 
 // Returns the index of |mode| in |modes| or not found.
 static uint64_t GetModeIndex(
     const display::DisplaySnapshot::DisplayModeList& modes,
     const display::DisplayMode* mode) {
@@ skipping 107 matching lines @@
 
   *out = base::MakeUnique<display::DisplaySnapshotMojo>(
       data.display_id(), origin, physical_size, type,
       data.is_aspect_preserving_scaling(), data.has_overscan(),
       data.has_color_correction_matrix(), display_name, file_path,
       data.product_id(), std::move(modes), std::move(edid), current_mode,
       native_mode, maximum_cursor_size);
   return true;
 }
 
-}  // namespace mojo
+}  // namespace mojo