Only store previous clip rects for PaintLayers that support subsequences.

third_party/WebKit/Source/core/paint/PrePaintTreeWalkTest.cpp

Index: third_party/WebKit/Source/core/paint/PrePaintTreeWalkTest.cpp
diff --git a/third_party/WebKit/Source/core/paint/PrePaintTreeWalkTest.cpp b/third_party/WebKit/Source/core/paint/PrePaintTreeWalkTest.cpp
index 814eec7b96dbfe350848ce90fbba512a53e04f65..520bd6290e2ad240d92e1bdb8e5b31353f450094 100644
--- a/third_party/WebKit/Source/core/paint/PrePaintTreeWalkTest.cpp
+++ b/third_party/WebKit/Source/core/paint/PrePaintTreeWalkTest.cpp
@@ -8,6 +8,7 @@
 #include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/PaintPropertyTreePrinter.h"
+#include "core/paint/PrePaintTreeWalk.h"
 #include "platform/graphics/paint/GeometryMapper.h"
 #include "platform/graphics/paint/ScrollPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
@@ -52,6 +53,11 @@ class PrePaintTreeWalkTest
     return frame_view->ScrollTranslation();
   }
 
+ protected:
+  PaintLayer* GetPaintLayerByElementId(const char* id) {
+    return ToLayoutBoxModelObject(GetLayoutObjectByElementId(id))->Layer();
+  }
+
  private:
   void SetUp() override {
     Settings::SetMockScrollbarsEnabled(true);
@@ -212,8 +218,8 @@ TEST_P(PrePaintTreeWalkTest, ClearSubsequenceCachingClipChangePosAbs) {
       "</style>"
       "<div id='parent' style='transform: translateZ(0); width: 100px;"
       "  height: 100px; position: absolute'>"
-      "  <div id='child' style='overflow: hidden; z-index: 0; width: 50px;"
-      "      height: 50px'>"
+      "  <div id='child' style='overflow: hidden; position: relative;"
+      "      z-index: 0; width: 50px; height: 50px'>"
       "    content"
       "  </div>"
       "</div>");
@@ -261,4 +267,32 @@ TEST_P(PrePaintTreeWalkTest, ClearSubsequenceCachingClipChangePosFixed) {
   EXPECT_TRUE(child_paint_layer->NeedsRepaint());
 }
 
+TEST_P(PrePaintTreeWalkTest, ClipRects) {
+  SetBodyInnerHTML(
+      "<div id='parent' style='isolation: isolate'>"
+      "  <div id='child' style='position: relative'>"
+      "    <div id='grandchild' style='isolation: isolate'>"
+      "      <div style='position: relative'></div>"
+      "    </div>"
+      "  </div>"
+      "</div>");
+
+  auto* parent = GetPaintLayerByElementId("parent");
+  auto* child = GetPaintLayerByElementId("child");
+  auto* grandchild = GetPaintLayerByElementId("grandchild");
+
+  EXPECT_TRUE(parent->PreviousPaintingClipRects());
+  EXPECT_FALSE(child->PreviousPaintingClipRects());
+  EXPECT_TRUE(grandchild->PreviousPaintingClipRects());
+
+  grandchild->ClearPreviousPaintingClipRects();
+  GetDocument().View()->UpdateAllLifecyclePhases();
+  // Still no rects, because the walk early-outed at the LayoutView.
+  EXPECT_FALSE(grandchild->PreviousPaintingClipRects());
+
+  GetDocument().View()->GetLayoutView()->SetNeedsPaintPropertyUpdate();
+  GetDocument().View()->UpdateAllLifecyclePhases();
+  EXPECT_TRUE(grandchild->PreviousPaintingClipRects());
+}
+
 }  // namespace blink