[Isolation]: Establish isolation on style & layout containment.

This patch adds style & layout containment as another criteria for when
we establish isolation.

R=chrishtr@chromium.org

Change-Id: I325edc499d41ea8580d138e982a358f74d13f22e
Reviewed-on: https://chromium-review.googlesource.com/c/1388747Reviewed-by: Mason Freed <masonfreed@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619964}

third_party/blink/renderer/core/paint/paint_property_tree_builder.cc

@@ -317,8 +317,12 @@ static bool NeedsIsolationNodes(const LayoutObject& object) {
     return false;
 
   // Paint containment establishes isolation.
-  if (object.ShouldApplyPaintContainment())
+  // Style & Layout containment also establish isolation.
+  if (object.ShouldApplyPaintContainment() ||
+      (object.ShouldApplyStyleContainment() &&
+       object.ShouldApplyLayoutContainment())) {
     return true;
+  }
 
   // Layout view establishes isolation with the exception of local roots (since
   // they are already essentially isolated).

third_party/blink/renderer/core/paint/paint_property_tree_builder_test.cc

@@ -3444,15 +3444,18 @@ TEST_P(PaintPropertyTreeBuilderTest, OverflowClipContentsTreeState) {
   CHECK_EXACT_VISUAL_RECT(LayoutRect(0, 0, 500, 600), child, clipper);
 }
 
-TEST_P(PaintPropertyTreeBuilderTest, ContainsPaintContentsTreeState) {
-  SetBodyInnerHTML(R"HTML(
+TEST_P(PaintPropertyTreeBuilderTest, ContainPaintOrStyleLayoutTreeState) {
+  for (const char* containment : {"paint", "style layout"}) {
+    SCOPED_TRACE(containment);
+    SetBodyInnerHTML(String::Format(R"HTML(
       <style>body { margin: 20px 30px; }</style>
       <div id='clipper'
-        style='contain: paint; width: 300px; height: 200px;'>
+          style='contain: %s; width: 300px; height: 200px;'>
         <div id='child'
             style='position: relative; width: 400px; height: 500px;'></div>
       </div>
-  )HTML");
+    )HTML",
+                                    containment));
 
     LayoutBoxModelObject* clipper =
         ToLayoutBoxModelObject(GetLayoutObjectByElementId("clipper"));
@@ -3479,12 +3482,20 @@ TEST_P(PaintPropertyTreeBuilderTest, ContainsPaintContentsTreeState) {
     // properties effect.
     EXPECT_EQ(clip_properties->EffectIsolationNode()->Parent(),
               clip_local_properties.Effect());
-  // Clip isolation node, however, is parented to the overflow clip, which is in
-  // turn parented to the local border box properties clip.
+    if (strcmp(containment, "paint") == 0) {
+      // If we contain paint, then clip isolation node is parented to the
+      // overflow clip, which is in turn parented to the local border box
+      // properties clip.
       EXPECT_EQ(clip_properties->ClipIsolationNode()->Parent(),
                 clip_properties->OverflowClip());
       EXPECT_EQ(clip_properties->OverflowClip()->Parent(),
                 clip_local_properties.Clip());
+    } else {
+      // Otherwise, the clip isolation node is parented to the local border box
+      // properties clip directly.
+      EXPECT_EQ(clip_properties->ClipIsolationNode()->Parent(),
+                clip_local_properties.Clip());
+    }
 
     // Verify transform:
 
@@ -3498,7 +3509,8 @@ TEST_P(PaintPropertyTreeBuilderTest, ContainsPaintContentsTreeState) {
       EXPECT_FALSE(DocScrollTranslation());
       EXPECT_TRUE(DocPreTranslation());
       // Isolation induces paint offset translation, so the node should be
-    // different from the doc node, but its parent is the same as the doc node.
+      // different from the doc node, but its parent is the same as the doc
+      // node.
       EXPECT_EQ(DocPreTranslation(), clipper->FirstFragment()
                                          .LocalBorderBoxProperties()
                                          .Transform()
@@ -3508,7 +3520,8 @@ TEST_P(PaintPropertyTreeBuilderTest, ContainsPaintContentsTreeState) {
       // not scroll (not enough content).
       EXPECT_TRUE(DocScrollTranslation());
       // Isolation induces paint offset translation, so the node should be
-    // different from the doc node, but its parent is the same as the doc node.
+      // different from the doc node, but its parent is the same as the doc
+      // node.
       EXPECT_EQ(DocScrollTranslation(), clipper->FirstFragment()
                                             .LocalBorderBoxProperties()
                                             .Transform()
@@ -3521,7 +3534,8 @@ TEST_P(PaintPropertyTreeBuilderTest, ContainsPaintContentsTreeState) {
               clipper->FirstFragment().LocalBorderBoxProperties().Clip());
     // Clip isolation node should be big enough to encompass all other clips,
     // including DocContentClip.
-  EXPECT_TRUE(clip_properties->ClipIsolationNode()->ClipRect().Rect().Contains(
+    EXPECT_TRUE(
+        clip_properties->ClipIsolationNode()->ClipRect().Rect().Contains(
             DocContentClip()->ClipRect().Rect()));
 
     // Verify contents properties and child properties:
@@ -3544,6 +3558,7 @@ TEST_P(PaintPropertyTreeBuilderTest, ContainsPaintContentsTreeState) {
     EXPECT_EQ(contents_properties.Effect(),
               child->FirstFragment().LocalBorderBoxProperties().Effect());
     CHECK_EXACT_VISUAL_RECT(LayoutRect(0, 0, 400, 500), child, clipper);
+  }
 }
 
 TEST_P(PaintPropertyTreeBuilderTest, OverflowScrollContentsTreeState) {