SetDeviceScaleFactorForTest

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index aeadc78f2fe40a9863c39daa451852a86f78cf9f..d971acf8d5565c9bfcd07ba8ad2efe930f597a18 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -183,9 +183,11 @@ DesktopWindowTreeHostX11::DesktopWindowTreeHostX11(
       urgency_hint_set_(false),
       activatable_(true),
       close_widget_factory_(this) {
+  display::Screen::GetScreen()->AddObserver(this);
 }
 
 DesktopWindowTreeHostX11::~DesktopWindowTreeHostX11() {
+  display::Screen::GetScreen()->RemoveObserver(this);
   window()->ClearProperty(kHostForRootWindow);
   aura::client::SetWindowMoveClient(window(), NULL);
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(this);
@@ -2036,6 +2038,17 @@ uint32_t DesktopWindowTreeHostX11::DispatchEvent(
   return ui::POST_DISPATCH_STOP_PROPAGATION;
 }
 
+void DesktopWindowTreeHostX11::OnDisplayMetricsChanged(
+    const display::Display& display,
+    uint32_t changed_metrics) {
+  display::Screen* screen = display::Screen::GetScreen();
+  if ((changed_metrics & DisplayObserver::DISPLAY_METRIC_DEVICE_SCALE_FACTOR) &&
+      screen->GetDisplayNearestWindow(window()).id() == display.id()) {
+    OnHostResized(bounds_in_pixels_.size());
+    ResetWindowRegion();
+  }
+}
+
 void DesktopWindowTreeHostX11::DelayedResize(const gfx::Size& size_in_pixels) {
   OnHostResized(size_in_pixels);
   ResetWindowRegion();