Apply both phsical bounding box and clip to composited bounds.

third_party/WebKit/Source/core/paint/PaintLayerTest.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintLayer.h"
 
 #include "core/html/HTMLIFrameElement.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
@@ skipping 40 matching lines @@
       "  width: 200px; background: lightblue; }</style>");
 
   PaintLayer* parentLayer =
       toLayoutBoxModelObject(getLayoutObjectByElementId("parent"))->layer();
   // Since "absposchild" is clipped by "parent", it should not expand the
   // composited bounds for "parent" beyond its intrinsic size of 150x150.
   EXPECT_EQ(LayoutRect(0, 0, 150, 150),
             parentLayer->boundingBoxForCompositing());
 }
 
+TEST_P(PaintLayerTest, CompositedBoundsTransformedChild) {
+  // TODO(chrishtr): fix this test for SPv2
+  if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+    return;
+
+  setBodyInnerHTML(
+      "<div id=parent style='overflow: scroll; will-change: transform'>"
+      "  <div class='target'"
+      "       style='position: relative; transform: skew(-15deg);'>"
+      "  </div>"
+      "  <div style='width: 1000px; height: 500px; background: lightgray'>"
+      "  </div>"
+      "</div>");
+
+  PaintLayer* parentLayer =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("parent"))->layer();
+  EXPECT_EQ(LayoutRect(0, 0, 784, 500),
+            parentLayer->boundingBoxForCompositing());
+}
+
 TEST_P(PaintLayerTest, PaintingExtentReflection) {
   setBodyInnerHTML(
       "<div id='target' style='background-color: blue; position: absolute;"
       "    width: 110px; height: 120px; top: 40px; left: 60px;"
       "    -webkit-box-reflect: below 3px'>"
       "</div>");
 
   PaintLayer* layer =
       toLayoutBoxModelObject(getLayoutObjectByElementId("target"))->layer();
   EXPECT_EQ(
@@ skipping 323 matching lines @@
   EXPECT_EQ(LayoutRect(0, 30, 50, 5), content->visualRect());
 
   scroller->getScrollableArea()->setScrollOffset(ScrollOffset(0, 20),
                                                  ProgrammaticScroll);
   document().view()->updateAllLifecyclePhases();
   EXPECT_EQ(LayoutRect(0, 30, 50, 10), contentLayer->visualRect());
   EXPECT_EQ(LayoutRect(0, 30, 50, 5), content->visualRect());
 }
 
 }  // namespace blink