Use the window coordinate for the autofill bounds.

components/autofill/content/renderer/password_generation_agent.cc

Index: components/autofill/content/renderer/password_generation_agent.cc
diff --git a/components/autofill/content/renderer/password_generation_agent.cc b/components/autofill/content/renderer/password_generation_agent.cc
index 4d1c8cc41eafca86a055ebf008fce5df223a2e90..6ad50b527be8be544cd6d4b5df2c72cf4636d739 100644
--- a/components/autofill/content/renderer/password_generation_agent.cc
+++ b/components/autofill/content/renderer/password_generation_agent.cc
@@ -411,18 +411,26 @@ bool PasswordGenerationAgent::TextDidChangeInTextField(
 }
 
 void PasswordGenerationAgent::ShowGenerationPopup() {
+  blink::WebRect bounding_box_in_window =
+      generation_element_.boundsInViewport();
+  render_frame()->GetRenderView()->convertViewportToWindow(
+      &bounding_box_in_window);
+
   Send(new AutofillHostMsg_ShowPasswordGenerationPopup(
-      routing_id(), gfx::RectF(generation_element_.boundsInViewport()),
+      routing_id(), gfx::RectF(bounding_box_in_window),
       generation_element_.maxLength(), *generation_form_data_->form));
 
   generation_popup_shown_ = true;
 }
 
 void PasswordGenerationAgent::ShowEditingPopup() {
+  blink::WebRect bounding_box_in_window =
+      generation_element_.boundsInViewport();
+  render_frame()->GetRenderView()->convertViewportToWindow(
+      &bounding_box_in_window);
   Send(new AutofillHostMsg_ShowPasswordEditingPopup(
-      routing_id(), gfx::RectF(generation_element_.boundsInViewport()),
+      routing_id(), gfx::RectF(bounding_box_in_window),
       *generation_form_data_->form));
-
   editing_popup_shown_ = true;
 }