Makes Screen functions take a const gfx::NativeView

ui/aura/test/test_screen.cc

 // Copyright (c) 2012 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/aura/test/test_screen.h"
 
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "ui/aura/env.h"
@@ skipping 140 matching lines @@
 
 int TestScreen::GetNumDisplays() const {
   return 1;
 }
 
 std::vector<display::Display> TestScreen::GetAllDisplays() const {
   return std::vector<display::Display>(1, display_);
 }
 
 display::Display TestScreen::GetDisplayNearestWindow(
-    gfx::NativeWindow window) const {
+    const gfx::NativeWindow window) const {
   return display_;
 }
 
 display::Display TestScreen::GetDisplayNearestPoint(
     const gfx::Point& point) const {
   return display_;
 }
 
 display::Display TestScreen::GetDisplayMatching(
     const gfx::Rect& match_rect) const {
   return display_;
 }
 
 void TestScreen::AddObserver(display::DisplayObserver* observer) {}
 
 void TestScreen::RemoveObserver(display::DisplayObserver* observer) {}
 
 TestScreen::TestScreen(const gfx::Rect& screen_bounds,
                        WindowTreeClient* window_tree_client)
     : host_(nullptr), ui_scale_(1.0f), window_tree_client_(window_tree_client) {
   static int64_t synthesized_display_id = 2000;
   display_.set_id(synthesized_display_id++);
   display_.SetScaleAndBounds(1.0f, screen_bounds);
 }
 
 }  // namespace aura