Bug 1476221 - Keep the bounding client rect of the 'FormAssist:AutoCompleteResults' message relative to the visual viewport. r=mstange

Depends on D6090

Differential Revision: https://phabricator.services.mozilla.com/D6091

--HG--
extra : moz-landing-system : lando

mobile/android/modules/FormAssistant.jsm

@@ -378,9 +378,17 @@ var FormAssistant = {
       scrollY += rect.top + parseInt(top);
     }
 
+    // The rect computed above is relative to the origin of the viewport frame,
+    // i.e. the layout viewport origin, but the consumer of the
+    // FormAssist::AutoCompleteResult messaage expects a rect relative to
+    // the visual viewport origin, so translate between the two.
+    let offsetX = {}, offsetY = {};
+    aElement.ownerGlobal.windowUtils
+        .getVisualViewportOffsetRelativeToLayoutViewport(offsetX, offsetY);
+
     return {
-      x: r.left + scrollX,
-      y: r.top + scrollY,
+      x: r.left + scrollX - offsetX.value,
+      y: r.top + scrollY - offsetY.value,
       w: r.width,
       h: r.height,
     };