Fix form validation bubble positioning at hidpi.

content/browser/renderer_host/render_widget_host_view_base.cc

Index: content/browser/renderer_host/render_widget_host_view_base.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_base.cc b/content/browser/renderer_host/render_widget_host_view_base.cc
index 23ebf837e36bbab83b0fdaa1ec25c9eba43e486f..826b209ebd7d4ad3cb585ff52be7b58bca33d222 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.cc
+++ b/content/browser/renderer_host/render_widget_host_view_base.cc
@@ -323,6 +323,12 @@ void RenderWidgetHostViewBase::FocusedNodeTouched(
   DVLOG(1) << "FocusedNodeTouched: " << editable;
 }
 
+float RenderWidgetHostViewBase::GetDeviceScaleFactor() const {
+  // Non-aura platforms don't have a conception of device scale factor, so
+  // return a no-op value if it gets used.
+  return 1.f;
+}
+
 uint32_t RenderWidgetHostViewBase::RendererFrameNumber() {
   return renderer_frame_number_;
 }