Scale client area, hit test mask and bounds by device_scale_factor.

services/ui/test_wm/test_wm.cc

Index: services/ui/test_wm/test_wm.cc
diff --git a/services/ui/test_wm/test_wm.cc b/services/ui/test_wm/test_wm.cc
index 58ba24aed2fe9c595d9da4223c8d193e11baef3f..fdefd64a351a5aea99e0156a0241167e51aa004c 100644
--- a/services/ui/test_wm/test_wm.cc
+++ b/services/ui/test_wm/test_wm.cc
@@ -16,6 +16,7 @@
 #include "services/ui/public/cpp/window_tree_client.h"
 #include "services/ui/public/cpp/window_tree_client_delegate.h"
 #include "ui/display/display.h"
+#include "ui/display/test/test_screen.h"
 
 namespace ui {
 namespace test {
@@ -25,11 +26,13 @@ class TestWM : public service_manager::Service,
                public ui::WindowManagerDelegate {
  public:
   TestWM() {}
-  ~TestWM() override {}
+  ~TestWM() override { display::Screen::SetScreenInstance(nullptr); }
 
  private:
   // service_manager::Service:
   void OnStart() override {
+    test_screen_ = base::MakeUnique<display::test::TestScreen>();
+    display::Screen::SetScreenInstance(test_screen_.get());
     window_tree_client_.reset(new ui::WindowTreeClient(this, this));
     window_tree_client_->ConnectAsWindowManager(context()->connector());
   }
@@ -105,6 +108,9 @@ class TestWM : public service_manager::Service,
   }
   void OnWmCancelMoveLoop(Window* window) override {}
 
+  // Dummy screen required to be the screen instance.
+  std::unique_ptr<display::test::TestScreen> test_screen_;
+
   ui::Window* root_ = nullptr;
   ui::WindowManagerClient* window_manager_client_ = nullptr;
   std::unique_ptr<ui::WindowTreeClient> window_tree_client_;