Pass device scale factor from display to ws.

services/ui/ws/platform_display.h

Index: services/ui/ws/platform_display.h
diff --git a/services/ui/ws/platform_display.h b/services/ui/ws/platform_display.h
index e68048ac0ffeef125c3aacb13f5ea562a76c8a96..633d9c6f09f1f8449ef3699cedf74fcbd63f1241 100644
--- a/services/ui/ws/platform_display.h
+++ b/services/ui/ws/platform_display.h
@@ -143,7 +143,9 @@ class DefaultPlatformDisplay : public PlatformDisplay,
       scoped_refptr<gpu::GpuChannelHost> gpu_channel) override;
 
  private:
-  void UpdateMetrics(const gfx::Rect& bounds, float device_scale_factor);
+  void UpdateMetrics(const gfx::Rect& bounds,
+                     const gfx::Size& pixel_size,
+                     float device_scale_factor);
 
   // Update the root_location of located events to be relative to the origin
   // of this display. For example, if the origin of this display is (1800, 0)