Only store previous clip rects for PaintLayers that support subsequen…

…ces.

To do this:

2. When updating paint properties, only invalidate painting optimizations like
subsequence for PaintLayers that support it (stacking context, SVG root), or
have clip-related properties

BUG=692614,711413
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2810503002
Cr-Commit-Position: refs/heads/master@{#464670}
(cherry picked from commit d1cf31c)

Review-Url: https://codereview.chromium.org/2832603002 .
Cr-Commit-Position: refs/branch-heads/3071@{#57}
Cr-Branched-From: a106f0a-refs/heads/master@{#464641}

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

@@ -2748,6 +2748,24 @@ bool PaintLayer::PaintsWithTransform(
           GetCompositingState() != kPaintsIntoOwnBacking);
 }
 
+bool PaintLayer::SupportsSubsequenceCaching() const {
+  // SVG paints atomically.
+  if (GetLayoutObject().IsSVGRoot())
+    return true;
+
+  // Create subsequence for only stacking contexts whose painting are atomic.
+  if (!StackingNode()->IsStackingContext())
+    return false;
+
+  // The layer doesn't have children. Subsequence caching is not worth it,
+  // because normally the actual painting will be cheap.
+  // SVG is also painted atomically.
+  if (!PaintLayerStackingNodeIterator(*StackingNode(), kAllChildren).Next())
+    return false;
+
+  return true;
+}
+
 ScrollingCoordinator* PaintLayer::GetScrollingCoordinator() {
   Page* page = GetLayoutObject().GetFrame()->GetPage();
   return (!page) ? nullptr : page->GetScrollingCoordinator();

third_party/WebKit/Source/core/paint/PaintLayer.h

@@ -584,6 +584,8 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
 
   bool PaintsWithTransform(GlobalPaintFlags) const;
 
+  bool SupportsSubsequenceCaching() const;
+
   // Returns true if background phase is painted opaque in the given rect.
   // The query rect is given in local coordinates.
   bool BackgroundIsKnownToBeOpaqueInRect(const LayoutRect&) const;
@@ -928,6 +930,9 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
   void SetPreviousPaintingClipRects(ClipRects& clip_rects) {
     previous_painting_clip_rects_ = &clip_rects;
   }
+  void ClearPreviousPaintingClipRects() {
+    previous_painting_clip_rects_.Clear();
+  }
 
   LayoutRect PreviousPaintDirtyRect() const {
     return previous_paint_dirty_rect_;

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

@@ -167,6 +167,9 @@ static bool ShouldCreateSubsequence(const PaintLayer& paint_layer,
   if (context.Printing())
     return false;
 
+  if (!paint_layer.SupportsSubsequenceCaching())
+    return false;
+
   // Don't create subsequence for a composited layer because if it can be
   // cached, we can skip the whole painting in GraphicsLayer::paint() with
   // CachedDisplayItemList.  This also avoids conflict of
@@ -185,20 +188,6 @@ static bool ShouldCreateSubsequence(const PaintLayer& paint_layer,
        kPaintLayerPaintingOverlayScrollbars | kPaintLayerUncachedClipRects))
     return false;
 
-  // Create subsequence for only stacking contexts whose painting are atomic.
-  // SVG is also painted atomically.
-  if (!paint_layer.StackingNode()->IsStackingContext() &&
-      !paint_layer.GetLayoutObject().IsSVGRoot())
-    return false;
-
-  // The layer doesn't have children. Subsequence caching is not worth because
-  // normally the actual painting will be cheap.
-  // SVG is also painted atomically.
-  if (!PaintLayerStackingNodeIterator(*paint_layer.StackingNode(), kAllChildren)
-           .Next() &&
-      !paint_layer.GetLayoutObject().IsSVGRoot())
-    return false;
-
   // When in FOUC-avoidance mode, don't cache any subsequences, to avoid having
   // to invalidate all of them when leaving this mode. There is an early-out in
   // BlockPainter::paintContents that may result in nothing getting painted in
@@ -346,6 +335,7 @@ PaintResult PaintLayerPainter::PaintLayerContents(
         SubsequenceRecorder::UseCachedSubsequenceIfPossible(context,
                                                             paint_layer_))
       return result;
+    DCHECK(paint_layer_.SupportsSubsequenceCaching());
     subsequence_recorder.emplace(context, paint_layer_);
   } else {
     should_clear_empty_paint_phase_flags = true;

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

@@ -286,6 +286,49 @@ TEST_P(PaintLayerTest, HasNonIsolatedDescendantWithBlendMode) {
   EXPECT_TRUE(parent->HasVisibleDescendant());
 }
 
+TEST_P(PaintLayerTest, SubsequenceCachingStackingContexts) {
+  SetBodyInnerHTML(
+      "<div id='parent' style='position:relative'>"
+      "  <div id='child1' style='position: relative'>"
+      "    <div id='grandchild1' style='position: relative'>"
+      "      <div style='position: relative'></div>"
+      "    </div>"
+      "  </div>"
+      "  <div id='child2' style='isolation: isolate'>"
+      "    <div style='position: relative'></div>"
+      "  </div>"
+      "</div>");
+  PaintLayer* parent = GetPaintLayerByElementId("parent");
+  PaintLayer* child1 = GetPaintLayerByElementId("child1");
+  PaintLayer* child2 = GetPaintLayerByElementId("child2");
+  PaintLayer* grandchild1 = GetPaintLayerByElementId("grandchild1");
+
+  EXPECT_FALSE(parent->SupportsSubsequenceCaching());
+  EXPECT_FALSE(child1->SupportsSubsequenceCaching());
+  EXPECT_TRUE(child2->SupportsSubsequenceCaching());
+  EXPECT_FALSE(grandchild1->SupportsSubsequenceCaching());
+
+  GetDocument()
+      .GetElementById("grandchild1")
+      ->setAttribute(HTMLNames::styleAttr, "isolation: isolate");
+  GetDocument().View()->UpdateAllLifecyclePhases();
+
+  EXPECT_FALSE(parent->SupportsSubsequenceCaching());
+  EXPECT_FALSE(child1->SupportsSubsequenceCaching());
+  EXPECT_TRUE(child2->SupportsSubsequenceCaching());
+  EXPECT_TRUE(grandchild1->SupportsSubsequenceCaching());
+}
+
+TEST_P(PaintLayerTest, SubsequenceCachingSVGRoot) {
+  SetBodyInnerHTML(
+      "<div id='parent' style='position: relative'>"
+      "  <svg id='svgroot' style='position: relative'></svg>"
+      "</div>");
+
+  PaintLayer* svgroot = GetPaintLayerByElementId("svgroot");
+  EXPECT_TRUE(svgroot->SupportsSubsequenceCaching());
+}
+
 TEST_P(PaintLayerTest, HasDescendantWithClipPath) {
   SetBodyInnerHTML(
       "<div id='parent' style='position:relative'>"

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

@@ -157,6 +157,14 @@ void PrePaintTreeWalk::InvalidatePaintLayerOptimizationsIfNeeded(
     context.ancestor_transformed_or_root_paint_layer = &paint_layer;
   }
 
+  // This code below checks whether any clips have changed that might:
+  // (a) invalidate optimizations made for a PaintLayer that supports
+  //     subsequence caching, or
+  // (b) impact clipping of descendant visual rects.
+  if (!paint_layer.SupportsSubsequenceCaching() &&
+      !paint_layer.GetLayoutObject().HasClipRelatedProperty())
+    return;
+
   const auto& ancestor =
       context.ancestor_transformed_or_root_paint_layer->GetLayoutObject();
   PropertyTreeState ancestor_state = *ancestor.LocalBorderBoxProperties();

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"
@@ -20,16 +21,18 @@
 
 namespace blink {
 
-typedef bool TestParamRootLayerScrolling;
+typedef std::pair<bool, bool> SlimmingPaintAndRootLayerScrolling;
 class PrePaintTreeWalkTest
-    : public ::testing::WithParamInterface<TestParamRootLayerScrolling>,
+    : public ::testing::WithParamInterface<SlimmingPaintAndRootLayerScrolling>,
       private ScopedSlimmingPaintV2ForTest,
+      private ScopedSlimmingPaintInvalidationForTest,
       private ScopedRootLayerScrollingForTest,
       public RenderingTest {
  public:
   PrePaintTreeWalkTest()
-      : ScopedSlimmingPaintV2ForTest(true),
-        ScopedRootLayerScrollingForTest(GetParam()),
+      : ScopedSlimmingPaintV2ForTest(GetParam().second),
+        ScopedSlimmingPaintInvalidationForTest(true),
+        ScopedRootLayerScrollingForTest(GetParam().first),
         RenderingTest(EmptyLocalFrameClient::Create()) {}
 
   const TransformPaintPropertyNode* FramePreTranslation() {
@@ -52,6 +55,11 @@ class PrePaintTreeWalkTest
     return frame_view->ScrollTranslation();
   }
 
+ protected:
+  PaintLayer* GetPaintLayerByElementId(const char* id) {
+    return ToLayoutBoxModelObject(GetLayoutObjectByElementId(id))->Layer();
+  }
+
  private:
   void SetUp() override {
     Settings::SetMockScrollbarsEnabled(true);
@@ -67,7 +75,15 @@ class PrePaintTreeWalkTest
   }
 };
 
-INSTANTIATE_TEST_CASE_P(All, PrePaintTreeWalkTest, ::testing::Bool());
+SlimmingPaintAndRootLayerScrolling g_prepaint_foo[] = {
+    SlimmingPaintAndRootLayerScrolling(false, false),
+    SlimmingPaintAndRootLayerScrolling(true, false),
+    SlimmingPaintAndRootLayerScrolling(false, true),
+    SlimmingPaintAndRootLayerScrolling(true, true)};
+
+INSTANTIATE_TEST_CASE_P(All,
+                        PrePaintTreeWalkTest,
+                        ::testing::ValuesIn(g_prepaint_foo));
 
 TEST_P(PrePaintTreeWalkTest, PropertyTreesRebuiltWithBorderInvalidation) {
   SetBodyInnerHTML(
@@ -135,6 +151,9 @@ TEST_P(PrePaintTreeWalkTest, PropertyTreesRebuiltWithCSSTransformInvalidation) {
 }
 
 TEST_P(PrePaintTreeWalkTest, PropertyTreesRebuiltWithOpacityInvalidation) {
+  // In SPv1 mode, we don't need or store property tree nodes for effects.
+  if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+    return;
   SetBodyInnerHTML(
       "<style>"
       "  .opacityA { opacity: 0.9; }"
@@ -212,8 +231,8 @@ 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>");
@@ -261,26 +280,4 @@ TEST_P(PrePaintTreeWalkTest, ClearSubsequenceCachingClipChangePosFixed) {
   EXPECT_TRUE(child_paint_layer->NeedsRepaint());
 }
 
-TEST_P(PrePaintTreeWalkTest, ClipChangeHasRadius) {
-  SetBodyInnerHTML(
-      "<style>"
-      "  #target {"
-      "    position: absolute;"
-      "    z-index: 0;"
-      "    overflow: hidden;"
-      "    width: 50px;"
-      "    height: 50px;"
-      "  }"
-      "</style>"
-      "<div id='target'></div>");
-
-  auto* target = GetDocument().GetElementById("target");
-  auto* target_object = ToLayoutBoxModelObject(target->GetLayoutObject());
-  target->setAttribute(HTMLNames::styleAttr, "border-radius: 5px");
-  GetDocument().View()->UpdateAllLifecyclePhasesExceptPaint();
-  EXPECT_TRUE(target_object->Layer()->NeedsRepaint());
-  // And should not trigger any assert failure.
-  GetDocument().View()->UpdateAllLifecyclePhases();
-}
-
 }  // namespace blink