Scale bounds in DesktopWindowTreeHostMus and in calls to SetBounds.

ui/views/mus/window_tree_host_mus.cc

Index: ui/views/mus/window_tree_host_mus.cc
diff --git a/ui/views/mus/window_tree_host_mus.cc b/ui/views/mus/window_tree_host_mus.cc
index e0ec32fe891991032ae27225d717864c2559a6dc..ffb4a827d2db2d8c8a6ae8907052b7bcb47b1062 100644
--- a/ui/views/mus/window_tree_host_mus.cc
+++ b/ui/views/mus/window_tree_host_mus.cc
@@ -10,6 +10,7 @@
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/events/event.h"
+#include "ui/gfx/geometry/dip_util.h"
 #include "ui/platform_window/stub/stub_window.h"
 #include "ui/views/mus/input_method_mus.h"
 #include "ui/views/mus/native_widget_mus.h"
@@ -57,7 +58,8 @@ WindowTreeHostMus::WindowTreeHostMus(NativeWidgetMus* native_widget,
   compositor()->SetWindow(window);
 
   // Initialize the stub platform window bounds to those of the ui::Window.
-  platform_window()->SetBounds(window->bounds());
+  platform_window()->SetBounds(gfx::ConvertRectToPixel(
+      compositor()->device_scale_factor(), window->bounds()));
 
   compositor()->SetHostHasTransparentBackground(true);
 }