NOT FOR REVIEW - Update comp-scrolling state at a well defined point in the pipeline.

LayoutTests/compositing/overflow/build-paint-order-list-where-opt-in-decisions-can-affect-each-other.html

Index: LayoutTests/compositing/overflow/build-paint-order-list-where-opt-in-decisions-can-affect-each-other.html
diff --git a/LayoutTests/compositing/overflow/build-paint-order-list-where-opt-in-decisions-can-affect-each-other.html b/LayoutTests/compositing/overflow/build-paint-order-list-where-opt-in-decisions-can-affect-each-other.html
index 0742db2f4f1fd1e48e59eb335edaac71bff10aad..95aef180510d08f06dfb06487116efa20c37db56 100644
--- a/LayoutTests/compositing/overflow/build-paint-order-list-where-opt-in-decisions-can-affect-each-other.html
+++ b/LayoutTests/compositing/overflow/build-paint-order-list-where-opt-in-decisions-can-affect-each-other.html
@@ -99,68 +99,71 @@
       var parentscrollinglayer = document.getElementById('parentscrollinglayer');
       var childscrollinglayer = document.getElementById('childscrollinglayer');
 
-      if (window.internals) {
-        var failure = false;
-
-        // Here we want to compare paint order lists before and after promotion
-        // to the actual stacking order as determined by hit-testing. So we
-        // first force the element not to promote, then compute its paint and
-        // stacking order lists. We then force the element to opt in, and
-        // generate the paint and stacking order lists after opt-in.
-        //
-        // The paint order lists should exactly match the stacking order lists
-        // (modulo children that fall outside of the hit-testing area
-        // on-screen), both before and after promotion.
-        parentscrollinglayer.style.webkitTransform = 'translateZ(0px)';
-        document.body.offsetTop;
-
-        window.internals.settings.setAcceleratedCompositingForOverflowScrollEnabled(false);
-        parentscrollinglayer.style.webkitTransform = '';
-
-        var oldStackingOrder = getStackingOrder();
-        var oldPaintOrder = getPaintOrder(childscrollinglayer);
-
-        window.internals.settings.setAcceleratedCompositingForOverflowScrollEnabled(true);
-        parentscrollinglayer.style.webkitTransform = 'translateZ(0px)';
-
-        var newStackingOrder = getStackingOrder();
-        var newPaintOrder = getPaintOrder(childscrollinglayer);
-
-        // The getPaintOrder() function should return a pair of paint orders.
-        // One before promotion and one after. This pair of lists should remain
-        // identical whether the element is actually currently promoted or not,
-        // its purpose is to generate hypothetical pre- and post-lists to
-        // determine if the element is promotable.
-        if (!comparePaintOrderLists(oldPaintOrder, newPaintOrder)) {
-          failure = true;
-          write("FAIL - paint order lists not identical before/after promotion");
-        }
-
-        if (!compareStackingOrderWithPaintOrder(oldStackingOrder, oldPaintOrder.beforePromote)) {
-          failure = true;
-          write("FAIL - paint order list before promote doesn't match stacking order");
-        }
-
-        if (!compareStackingOrderWithPaintOrder(newStackingOrder, oldPaintOrder.afterPromote)) {
-          failure = true;
-          write("FAIL - paint order list after promote doesn't match stacking order");
-        }
-
-        var childScrollingLayerOccurrences = countOccurrencesOfElementInPaintOrderList(oldPaintOrder.beforePromote, childscrollinglayer);
-        if (childScrollingLayerOccurrences !== 1) {
-          failure = true;
-          write("FAIL - paint order list before promote contains " + childScrollingLayerOccurrences + " occurrences of child scrolling layer. Should be exactly 1.");
-        }
-
-        childScrollingLayerOccurrences = countOccurrencesOfElementInPaintOrderList(oldPaintOrder.afterPromote, childscrollinglayer);
-        if (childScrollingLayerOccurrences !== 1) {
-          failure = true;
-          write("FAIL - paint order list after promote contains " + childScrollingLayerOccurrences + " occurrences of child scrolling layer. Should be exactly 1.");
-        }
-
-        if(!failure)
-          write("PASS - did not crash.");
+      if (window.internals)
+        return;
+
+      var failure = false;
+
+      // Here we want to compare paint order lists before and after promotion
+      // to the actual stacking order as determined by hit-testing. So we
+      // first force the element not to promote, then compute its paint and
+      // stacking order lists. We then force the element to opt in, and
+      // generate the paint and stacking order lists after opt-in.
+      //
+      // The paint order lists should exactly match the stacking order lists
+      // (modulo children that fall outside of the hit-testing area
+      // on-screen), both before and after promotion.
+      parentscrollinglayer.style.webkitTransform = 'translateZ(0px)';
+      document.body.offsetTop;
+
+      window.internals.setNeedsCompositedScrolling(parentscrollinglayer, 
+          window.internals.FORCE_COMPOSITED_SCROLLING_OFF);
+      parentscrollinglayer.style.webkitTransform = '';
+
+      var oldStackingOrder = getStackingOrder();
+      var oldPaintOrder = getPaintOrder(childscrollinglayer);
+
+      window.internals.setNeedsCompositedScrolling(parentscrollinglayer, 
+          window.internals.FORCE_COMPOSITED_SCROLLING_ON);
+      parentscrollinglayer.style.webkitTransform = 'translateZ(0px)';
+
+      var newStackingOrder = getStackingOrder();
+      var newPaintOrder = getPaintOrder(childscrollinglayer);
+
+      // The getPaintOrder() function should return a pair of paint orders.
+      // One before promotion and one after. This pair of lists should remain
+      // identical whether the element is actually currently promoted or not,
+      // its purpose is to generate hypothetical pre- and post-lists to
+      // determine if the element is promotable.
+      if (!comparePaintOrderLists(oldPaintOrder, newPaintOrder)) {
+        failure = true;
+        write("FAIL - paint order lists not identical before/after promotion");
+      }
+
+      if (!compareStackingOrderWithPaintOrder(oldStackingOrder, oldPaintOrder.beforePromote)) {
+        failure = true;
+        write("FAIL - paint order list before promote doesn't match stacking order");
       }
+
+      if (!compareStackingOrderWithPaintOrder(newStackingOrder, oldPaintOrder.afterPromote)) {
+        failure = true;
+        write("FAIL - paint order list after promote doesn't match stacking order");
+      }
+
+      var childScrollingLayerOccurrences = countOccurrencesOfElementInPaintOrderList(oldPaintOrder.beforePromote, childscrollinglayer);
+      if (childScrollingLayerOccurrences !== 1) {
+        failure = true;
+        write("FAIL - paint order list before promote contains " + childScrollingLayerOccurrences + " occurrences of child scrolling layer. Should be exactly 1.");
+      }
+
+      childScrollingLayerOccurrences = countOccurrencesOfElementInPaintOrderList(oldPaintOrder.afterPromote, childscrollinglayer);
+      if (childScrollingLayerOccurrences !== 1) {
+        failure = true;
+        write("FAIL - paint order list after promote contains " + childScrollingLayerOccurrences + " occurrences of child scrolling layer. Should be exactly 1.");
+      }
+
+      if(!failure)
+        write("PASS - did not crash.");
     }
 
     window.addEventListener('load', doTest, false);