Fix form validation bubble positioning at hidpi.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index b5ed661870678988ded999fc0bef7927db7e2181..a9b1be0ab381a4868eaf96e26b6bbef723a84d2a 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -2026,6 +2026,10 @@ bool RenderWidgetHostViewAura::OnShowContextMenu(
 #endif  // defined(OS_WIN)
 }
 
+float RenderWidgetHostViewAura::GetDeviceScaleFactor() const {
+  return device_scale_factor_;
+}
+
 void RenderWidgetHostViewAura::SetSelectionControllerClientForTest(
     std::unique_ptr<TouchSelectionControllerClientAura> client) {
   selection_controller_client_.swap(client);