Exclude elements with overflow-anchor:none from anchor node selection

third_party/WebKit/Source/core/layout/ScrollAnchorTest.cpp

 // Copyright 2015 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/layout/ScrollAnchor.h"
 
 #include "core/dom/ClientRect.h"
 #include "core/frame/VisualViewport.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutTestHelper.h"
@@ skipping 543 matching lines @@
     ScrollableArea* viewport = layoutViewport();
 
     scrollLayoutViewport(DoubleSize(0, 200));
     setHeight(document().getElementById("float"), 600);
 
     EXPECT_EQ(200, viewport->scrollPosition().y());
     EXPECT_EQ(document().getElementById("float")->layoutObject(),
         scrollAnchor(viewport).anchorObject());
 }
 
+// Test then an element and its children are not selected as the anchor when
+// it has the overflow-anchor property set to none.
+TEST_F(ScrollAnchorTest, OptOutElement)
+{
+    setBodyInnerHTML(
+        "<style>"
+        "     body { height: 1000px }"
+        "     .div {"
+        "          height: 100px; width: 100px;"
+        "          border: 1px solid gray; background-color: #afa;"
+        "     }"
+        "     #innerDiv {"
+        "          height: 50px; width: 50px;"
+        "          border: 1px solid gray; background-color: pink;"
+        "     }"
+        "</style>"
+        "<div id='changer'></div>"
+        "<div class='div' id='firstDiv'><div id='innerDiv'></div></div>"
+        "<div class='div' id='secondDiv'></div>");
+
+    ScrollableArea* viewport = layoutViewport();
+    scrollLayoutViewport(DoubleSize(0, 50));
+
+    // No opt-out.
+    setHeight(document().getElementById("changer"), 100);
+    EXPECT_EQ(150, viewport->scrollPosition().y());
+    EXPECT_EQ(document().getElementById("innerDiv")->layoutObject(),
+        scrollAnchor(viewport).anchorObject());
+
+    // Clear anchor and opt-out element.
+    scrollLayoutViewport(DoubleSize(0, 10));
+    document().getElementById("firstDiv")->setAttribute(HTMLNames::styleAttr,
+        AtomicString("overflow-anchor: none"));
+    update();
+
+    // Opted out element and it's children skipped.
+    setHeight(document().getElementById("changer"), 200);
+    EXPECT_EQ(260, viewport->scrollPosition().y());
+    EXPECT_EQ(document().getElementById("secondDiv")->layoutObject(),
+        scrollAnchor(viewport).anchorObject());
+}
+
 TEST_F(ScrollAnchorTest, OptOutBody)
 {
     setBodyInnerHTML(
         "<style>"
         "    body { height: 2000px; overflow-anchor: none; }"
         "    #scroller { overflow: scroll; width: 500px; height: 300px; }"
         "    .anchor {"
         "        position:relative; height: 100px; width: 150px;"
         "        background-color: #afa; border: 1px solid gray;"
         "    }"
@@ skipping 208 matching lines @@
         "<div id=c></div>"
         "<div id=d></div>");
 
     checkCorner("b", Corner::TopRight, DoublePoint(-20,  20),  DoubleSize(0, 0));
     checkCorner("a", Corner::TopRight, DoublePoint(-420, 20),  DoubleSize(400, 0));
     checkCorner("d", Corner::TopRight, DoublePoint(-20,  320), DoubleSize(0, -300));
     checkCorner("c", Corner::TopRight, DoublePoint(-420, 320), DoubleSize(400, -300));
 }
 
 }