Disable scroll anchoring when in printing mode

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"
+#include "core/page/PrintContext.h"
 #include "core/paint/PaintLayerScrollableArea.h"
 #include "platform/testing/HistogramTester.h"
 
 namespace blink {
 
 using Corner = ScrollAnchor::Corner;
 
 class ScrollAnchorTest : public RenderingTest {
  public:
   ScrollAnchorTest() {
@@ skipping 813 matching lines @@
 
   // Scroll anchoring should be applied to #rootScroller.
   EXPECT_EQ(1000, scroller->scrollOffset().height());
   EXPECT_EQ(document().getElementById("target")->layoutObject(),
             scrollAnchor(scroller).anchorObject());
   // Scroll anchoring should not apply within main frame.
   EXPECT_EQ(0, layoutViewport()->scrollOffset().height());
   EXPECT_EQ(nullptr, scrollAnchor(layoutViewport()).anchorObject());
 }
 
+// This test verifies that scroll anchoring is disabled when the document is in
+// printing mode.
+TEST_F(ScrollAnchorTest, AnchoringDisabledForPrinting) {
+  setBodyInnerHTML(
+      "<style> body { height: 1000px } div { height: 100px } </style>"
+      "<div id='block1'>abc</div>"
+      "<div id='block2'>def</div>");
+
+  ScrollableArea* viewport = layoutViewport();
+  scrollLayoutViewport(ScrollOffset(0, 150));
+
+  // This will trigger printing and layout.
+  PrintContext::numberOfPages(document().frame(), FloatSize(500, 500));
+
+  EXPECT_EQ(150, viewport->scrollOffsetInt().height());
+  EXPECT_EQ(nullptr, scrollAnchor(viewport).anchorObject());
+}
+
 class ScrollAnchorCornerTest : public ScrollAnchorTest {
  protected:
   void checkCorner(Corner corner,
                    ScrollOffset startOffset,
                    ScrollOffset expectedAdjustment) {
     ScrollableArea* viewport = layoutViewport();
     Element* element = document().getElementById("changer");
 
     viewport->setScrollOffset(startOffset, UserScroll);
     element->setAttribute(HTMLNames::classAttr, "change");
@@ skipping 125 matching lines @@
 
   scrollLayoutViewport(ScrollOffset(-50, 0));
 
   a->setAttribute(HTMLNames::styleAttr, "width: 200px");
   b->setAttribute(HTMLNames::styleAttr, "height: 150px");
   update();
   EXPECT_EQ(ScrollOffset(-100, 150), viewport->scrollOffset());
   EXPECT_EQ(c->layoutObject(), scrollAnchor(viewport).anchorObject());
 }
 }