Update contentHeight algorithms

src/service/viewport/viewport-binding-ios-embed-sd.js

@@ -396,15 +396,13 @@ export class ViewportBindingIosEmbedShadowRoot_ {
 
   /** @override */
   getContentHeight() {
-    // The reparented body inside scroller will have the correct content height.
-    // Body is overflow: hidden so that the scrollHeight include the margins of
-    // body's first and last child.
-    // Body height doesn't include paddingTop on the parent, so we add on the
-    // position of the body from the top of the viewport and subtract the
-    // scrollTop (as position relative to the viewport changes as you scroll).
-    return this.wrapper_./*OK*/scrollHeight
+    const scrollingElement = this.wrapper_;
+    const style = getComputedStyle(scrollingElement);
+    return scrollingElement./*OK*/scrollHeight
         + this.paddingTop_
-        + this.getBorderTop();
+        + this.getBorderTop()
+        + parseInt(style.marginTop, 10)
+        + parseInt(style.marginBottom, 10);
   }
 
   /** @override */

src/service/viewport/viewport-binding-ios-embed-wrapper.js

@@ -234,14 +234,12 @@ export class ViewportBindingIosEmbedWrapper_ {
 
   /** @override */
   getContentHeight() {
-    // The reparented body inside wrapper will have the correct content height.
-    // Body is overflow: hidden so that the scrollHeight include the margins of
-    // body's first and last child.
-    // Body height doesn't include paddingTop on the parent, so we add on the
-    // position of the body from the top of the viewport and subtract the
-    // scrollTop (as position relative to the viewport changes as you scroll).
-    const rect = this.win.document.body./*OK*/getBoundingClientRect();
-    return rect.height + rect.top + this.getScrollTop();
+    const scrollingElement = this.wrapper_;
+    const style = getComputedStyle(scrollingElement);
+    return scrollingElement./*OK*/scrollHeight
+        + this.getBorderTop()
+        + parseInt(style.marginTop, 10)
+        + parseInt(style.marginBottom, 10);
   }
 
   /** @override */

src/service/viewport/viewport-binding-natural.js

@@ -195,14 +195,11 @@ export class ViewportBindingNatural_ {
 
   /** @override */
   getContentHeight() {
-    // The reparented body inside wrapper will have the correct content height.
-    // Body is overflow: hidden so that the scrollHeight include the margins of
-    // body's first and last child.
-    // Body height doesn't include paddingTop on the parent, so we add on the
-    // position of the body from the top of the viewport and subtract the
-    // scrollTop (as position relative to the viewport changes as you scroll).
-    const rect = this.win.document.body./*OK*/getBoundingClientRect();
-    return rect.height + rect.top + this.getScrollTop();
+    const scrollingElement = this.getScrollingElement();
+    const style = getComputedStyle(scrollingElement);
+    return scrollingElement./*OK*/scrollHeight
+        + parseInt(style.marginTop, 10)
+        + parseInt(style.marginBottom, 10);
   }
 
   /** @override */