SetDeviceScaleFactorForTest

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
index b648c0062a7517f66db480ce0221e8f825effacd..37eb23dfac0e5bd91427f97c17f892b7c3dacc43 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h
@@ -17,6 +17,7 @@
 #include "base/observer_list.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/cursor/cursor_loader_x11.h"
+#include "ui/display/display_observer.h"
 #include "ui/events/platform/platform_event_dispatcher.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/rect.h"
@@ -43,7 +44,8 @@ class X11WindowEventFilter;
 class VIEWS_EXPORT DesktopWindowTreeHostX11
     : public DesktopWindowTreeHost,
       public aura::WindowTreeHost,
-      public ui::PlatformEventDispatcher {
+      public ui::PlatformEventDispatcher,
+      public display::DisplayObserver {
  public:
   DesktopWindowTreeHostX11(
       internal::NativeWidgetDelegate* native_widget_delegate,
@@ -246,6 +248,12 @@ class VIEWS_EXPORT DesktopWindowTreeHostX11
   bool CanDispatchEvent(const ui::PlatformEvent& event) override;
   uint32_t DispatchEvent(const ui::PlatformEvent& event) override;
 
+  // display::DisplayObserver:
+  void OnDisplayAdded(const display::Display& display) override {}
+  void OnDisplayRemoved(const display::Display& display) override {}
+  void OnDisplayMetricsChanged(const display::Display& display,
+                               uint32_t changed_metrics) override;
+
   void DelayedResize(const gfx::Size& size_in_pixels);
 
   gfx::Rect GetWorkAreaBoundsInPixels() const;