No vertical bars if 'vertical-policy' disabled

When 'vertical-scroll' policy is disabled in a document, the contents cannot be scrolled (will not be user-input scrollable and targeted for gesture scroll). However, currently disabling 'vertical-scroll' still leaves the vertical scrollbars behind; the bars position cannot be changed however. This CL fixes the issue by hiding the vertical scrollbars for scrollable elements inside documents where the policy is enforced (i.e., disabled). Bug: 898151 Change-Id: If01925e27184a7370d5b12583dc73bc946f2c6e2 Reviewed-on: https://chromium-review.googlesource.com/c/1305878 Commit-Queue: Ehsan Karamad <ekaramad@chromium.org> Reviewed-by: David Bokan <bokan@chromium.org> Cr-Commit-Position: refs/heads/master@{#604420}

No vertical bars if 'vertical-policy' disabled
When 'vertical-scroll' policy is disabled in a document, the contents cannot be scrolled (will not be user-input scrollable and targeted for gesture scroll). However, currently disabling 'vertical-scroll' still leaves the vertical scrollbars behind; the bars position cannot be changed however. This CL fixes the issue by hiding the vertical scrollbars for scrollable elements inside documents where the policy is enforced (i.e., disabled). Bug: 898151 Change-Id: If01925e27184a7370d5b12583dc73bc946f2c6e2 Reviewed-on: https://chromium-review.googlesource.com/c/1305878 Commit-Queue: Ehsan Karamad <ekaramad@chromium.org> Reviewed-by: David Bokan <bokan@chromium.org> Cr-Commit-Position: refs/heads/master@{#604420}
3973180d · Ehsan Karamad · Commit Bot · 8c8047ec · 3973180d · 3973180d
Commit 3973180d authored Oct 31, 2018 by Ehsan Karamad Committed by Commit Bot Oct 31, 2018
3 changed files
--- a/third_party/WebKit/LayoutTests/external/wpt/feature-policy/experimental-features/resources/vertical-scroll-scrollbar-ref.html
+++ b/third_party/WebKit/LayoutTests/external/wpt/feature-policy/experimental-features/resources/vertical-scroll-scrollbar-ref.html
+<!doctype html>
+<title>Ref: vertical-scroll test for scrollbar</title>
+<iframe src="/feature-policy/experimental-features/resources/vertical-scroll-scrollable-content.html"></iframe>
+<script>
+  let iframe = document.querySelector("iframe");
+  let overflow_y = "visible";
+  if (window.location.search.indexOf("no-vertical-scrollbar") !== -1)
+    overflow_y = "hidden"
+  iframe.addEventListener("load", () => {
+    iframe.contentDocument.body.style.overflowY = overflow_y;
+  });
+</script>
+
--- a/third_party/WebKit/LayoutTests/external/wpt/feature-policy/experimental-features/vertical-scroll-disabled-scrollbar-tentative.html
+++ b/third_party/WebKit/LayoutTests/external/wpt/feature-policy/experimental-features/vertical-scroll-disabled-scrollbar-tentative.html
+<!doctype html>
+<title>vertical-scroll test for vertical scrollbar</title>
+<link rel="match" href="/feature-policy/experimental-features/resources/vertical-scroll-scrollbar-ref.html?no-vertical-scrollbar">
+<iframe src="/feature-policy/experimental-features/resources/vertical-scroll-scrollable-content.html" allow="vertical-scroll 'none'"></iframe>
--- a/third_party/blink/renderer/core/paint/paint_layer_scrollable_area.cc
+++ b/third_party/blink/renderer/core/paint/paint_layer_scrollable_area.cc
@@ -1562,6 +1562,13 @@ bool PaintLayerScrollableArea::SetHasVerticalScrollbar(bool has_scrollbar) {
  if (FreezeScrollbarsScope::ScrollbarsAreFrozen())
    return false;

+  if (GetLayoutBox()->GetDocument().IsVerticalScrollEnforced()) {
+    // When the policy is enforced the contents of document cannot be scrolled.
+    // This would make rendering a scrollbar look strange
+    // (https://crbug.com/898151).
+    return false;
+  }
+
  if (has_scrollbar == HasVerticalScrollbar())
    return false;