aura: Remove WindowTreeHost::OnDeviceScaleFactorChanged.

ui/aura/window_tree_host_x11.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/window_tree_host_x11.h"
 
 #include <strings.h>
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/extensions/Xrandr.h>
@@ skipping 591 matching lines @@
       xevent.xmotion.x_root = point.x();
       xevent.xmotion.y_root = point.y();
     }
     default:
       break;
   }
   XSendEvent(xdisplay_, xwindow_, False, 0, &xevent);
   XFlush(xdisplay_);
 }
 
-void WindowTreeHostX11::OnDeviceScaleFactorChanged(
-    float device_scale_factor) {
-}
-
 void WindowTreeHostX11::SetCursorNative(gfx::NativeCursor cursor) {
   if (cursor == current_cursor_)
     return;
   current_cursor_ = cursor;
   SetCursorInternal(cursor);
 }
 
 void WindowTreeHostX11::MoveCursorToNative(const gfx::Point& location) {
   XWarpPointer(xdisplay_, None, x_root_window_, 0, 0, 0, 0,
                bounds_.x() + location.x(),
@@ skipping 102 matching lines @@
 }
 
 namespace test {
 
 void SetUseOverrideRedirectWindowByDefault(bool override_redirect) {
   default_override_redirect = override_redirect;
 }
 
 }  // namespace test
 }  // namespace aura