SetDeviceScaleFactorForTest

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index d02a06c0be5b8d39b66ab5248d7d37d6047c079b..9870dab279e477787fa7cfa5ceba26fa2a422b7c 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -17,6 +17,7 @@
 #include "ui/base/win/shell.h"
 #include "ui/compositor/compositor_constants.h"
 #include "ui/compositor/paint_context.h"
+#include "ui/display/display.h"
 #include "ui/display/win/dpi.h"
 #include "ui/display/win/screen_win.h"
 #include "ui/gfx/geometry/insets.h"
@@ -87,9 +88,11 @@ DesktopWindowTreeHostWin::DesktopWindowTreeHostWin(
       pending_close_(false),
       has_non_client_view_(false),
       tooltip_(NULL) {
+  display::Screen::GetScreen()->AddObserver(this);
 }
 
 DesktopWindowTreeHostWin::~DesktopWindowTreeHostWin() {
+  display::Screen::GetScreen()->RemoveObserver(this);
   // WARNING: |content_window_| has been destroyed by the time we get here.
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(this);
   DestroyDispatcher();
@@ -599,6 +602,18 @@ void DesktopWindowTreeHostWin::OnWindowHidingAnimationCompleted() {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// DesktopWindowTreeHostWin, DisplayObserver implementation:
+void DesktopWindowTreeHostWin::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()) {
+    HandleWindowScaleFactorChanged(display.device_scale_factor());
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHostWin, HWNDMessageHandlerDelegate implementation:
 
 bool DesktopWindowTreeHostWin::HasNonClientView() const {