content-visibility: Increase the auto intersection margin to 150%.

This patch increases the viewport intersection margin for
content-visibility: auto to 150% of the viewport.

This prevents excessive 'checkerboarding' from lack of rendered
content on quick flings.

R=chrishtr@chromium.org
TEST=Tested with scrollBy({ top: 10000, behavior: 'smooth' }) on FB.

Change-Id: I70d3ef371d5aeb943dca26d6decae97184db446b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2453029
Commit-Queue: vmpstr <vmpstr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814799}

third_party/blink/renderer/core/display_lock/display_lock_context_test.cc

@@ -2824,10 +2824,10 @@ TEST_F(DisplayLockContextRenderingTest,
        AutoReachesStableStateOnContentSmallerThanLockedSize) {
   SetHtmlInnerHTML(R"HTML(
     <style>
-      .spacer { height: 10000px; }
+      .spacer { height: 20000px; }
       .auto {
         content-visibility: auto;
-        contain-intrinsic-size: 1px 10000px;
+        contain-intrinsic-size: 1px 20000px;
       }
       .auto > div {
         height: 3000px;
@@ -2842,7 +2842,7 @@ TEST_F(DisplayLockContextRenderingTest,
 
   UpdateAllLifecyclePhasesForTest();
 
-  GetDocument().scrollingElement()->setScrollTop(19000);
+  GetDocument().scrollingElement()->setScrollTop(29000);
 
   Element* element = GetDocument().getElementById("e1");
 
@@ -2852,35 +2852,35 @@ TEST_F(DisplayLockContextRenderingTest,
   // Initially we start with locked in the viewport.
   UpdateAllLifecyclePhasesForTest();
   EXPECT_TRUE(element->GetDisplayLockContext()->IsLocked());
-  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 19000.);
+  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 29000.);
 
   // It gets unlocked because it's in the viewport.
   UpdateAllLifecyclePhasesForTest();
   EXPECT_FALSE(element->GetDisplayLockContext()->IsLocked());
-  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 19000.);
+  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 29000.);
 
   // By unlocking it, it shrinks so next time it gets relocked.
   UpdateAllLifecyclePhasesForTest();
   EXPECT_TRUE(element->GetDisplayLockContext()->IsLocked());
-  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 19000.);
+  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 29000.);
 
   // It again gets unlocked and shrink.
   UpdateAllLifecyclePhasesForTest();
   EXPECT_FALSE(element->GetDisplayLockContext()->IsLocked());
-  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 19000.);
+  EXPECT_EQ(GetDocument().scrollingElement()->scrollTop(), 29000.);
 
   // On the next relock we select the following element as an anchor and thus
   // the scroll top changes to be higher.
   UpdateAllLifecyclePhasesForTest();
   EXPECT_TRUE(element->GetDisplayLockContext()->IsLocked());
-  EXPECT_GT(GetDocument().scrollingElement()->scrollTop(), 19000.);
+  EXPECT_GT(GetDocument().scrollingElement()->scrollTop(), 29000.);
 
   // Subsequent updates no longer unlock the element because even if its locked
   // state it is far enough off-screen.
   for (int i = 0; i < 5; ++i) {
     UpdateAllLifecyclePhasesForTest();
     EXPECT_TRUE(element->GetDisplayLockContext()->IsLocked());
-    EXPECT_GT(GetDocument().scrollingElement()->scrollTop(), 19000.);
+    EXPECT_GT(GetDocument().scrollingElement()->scrollTop(), 29000.);
   }
 }
 
@@ -3019,5 +3019,4 @@ TEST_F(DisplayLockContextTest, GraphicsLayerBitsNotCheckedInLockedSubtree) {
   EXPECT_FALSE(
       target_layer->GetCompositedLayerMapping()->NeedsGraphicsLayerUpdate());
 }
-
 }  // namespace blink

third_party/blink/renderer/core/display_lock/display_lock_document_state.cc

@@ -88,10 +88,11 @@ IntersectionObserver& DisplayLockDocumentState::EnsureIntersectionObserver() {
     // have run. This means for the duration of the idle time that follows, we
     // should always have clean layout.
     //
-    // Note that we use 50% margin (on the viewport) so that we get the
+    // Note that we use 150% margin (on the viewport) so that we get the
     // observation before the element enters the viewport.
     intersection_observer_ = IntersectionObserver::Create(
-        {Length::Percent(50.f)}, {std::numeric_limits<float>::min()}, document_,
+        {Length::Percent(150.f)}, {std::numeric_limits<float>::min()},
+        document_,
         WTF::BindRepeating(
             &DisplayLockDocumentState::ProcessDisplayLockActivationObservation,
             WrapWeakPersistent(this)),

third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-075-ref.html

@@ -9,10 +9,10 @@
 
 <style>
 .small_child {
-  height: 500px;
+  height: 1000px;
 }
 .large_child {
-  height: 5000px;
+  height: 20000px;
   position: relative;
 }
 #target {

third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-075.html

@@ -12,10 +12,10 @@
 <style>
 .auto {
   content-visibility: auto;
-  contain-intrinsic-size: 1px 500px;
+  contain-intrinsic-size: 1px 1000px;
 }
 .child {
-  height: 5000px;
+  height: 20000px;
   position: relative;
 }
 #target {

third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-076-ref.html

@@ -9,10 +9,10 @@
 
 <style>
 .small_child {
-  height: 500px;
+  height: 1000px;
 }
 .large_child {
-  height: 5000px;
+  height: 20000px;
   position: relative;
 }
 #target {

third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-076.html

@@ -12,10 +12,10 @@
 <style>
 .auto {
   content-visibility: auto;
-  contain-intrinsic-size: 1px 500px;
+  contain-intrinsic-size: 1px 1000px;
 }
 .child {
-  height: 5000px;
+  height: 20000px;
   position: relative;
 }
 #target {