Fix render surface occlusion with pixel-moving filters

We have been correctly ignoring occlusion from outside of the subtree
of a pixel-moving filter in the stack of OcclusionTracker (which leads
to correct occlusion inside of the subtree), but when we get the
occlusion of a render surface, previously we returned the current
occlusion of the parent render surface even if the current render
surface has pixel-moving filter, causing the render surface incorrectly
occluded.

Now add a flag in the stack indicating that the render surface doesn't
inherit parent occlusion, and
OcclusionTracker::GetCurrentOcclusionForContributingSurface() should
not return the parent occlusion when the flag is set.

Bug: 1040288
Change-Id: I505b079d62186a404b1be1c83c6cbccc89c10b8f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1994102Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#730215}

cc/trees/occlusion_tracker.cc

@@ -37,7 +37,7 @@ Occlusion OcclusionTracker::GetCurrentOcclusionForLayer(
 Occlusion OcclusionTracker::GetCurrentOcclusionForContributingSurface(
     const gfx::Transform& draw_transform) const {
   DCHECK(!stack_.empty());
-  if (stack_.size() < 2)
+  if (stack_.size() < 2 || stack_.back().ignores_parent_occlusion)
     return Occlusion();
   // A contributing surface doesn't get occluded by things inside its own
   // surface, so only things outside the surface can occlude it. That occlusion
@@ -49,10 +49,12 @@ Occlusion OcclusionTracker::GetCurrentOcclusionForContributingSurface(
 
 const RenderSurfaceImpl*
 OcclusionTracker::OcclusionSurfaceForContributingSurface() const {
+  if (stack_.size() < 2 || stack_.back().ignores_parent_occlusion)
+    return nullptr;
   // A contributing surface doesn't get occluded by things inside its own
   // surface, so only things outside the surface can occlude it. That occlusion
   // is found just below the top of the stack (if it exists).
-  return (stack_.size() < 2) ? nullptr : stack_[stack_.size() - 2].target;
+  return stack_[stack_.size() - 2].target;
 }
 
 void OcclusionTracker::EnterLayer(
@@ -162,8 +164,10 @@ void OcclusionTracker::EnterRenderTarget(
       !entering_unoccluded_subtree &&
       have_transform_from_screen_to_new_target &&
       !entering_root_target;
-  if (!copy_outside_occlusion_forward)
+  if (!copy_outside_occlusion_forward) {
+    stack_.back().ignores_parent_occlusion = true;
     return;
+  }
 
   size_t last_index = stack_.size() - 1;
   gfx::Transform old_target_to_new_target_transform(

cc/trees/occlusion_tracker.h

@@ -64,6 +64,7 @@ class CC_EXPORT OcclusionTracker {
     const RenderSurfaceImpl* target;
     SimpleEnclosedRegion occlusion_from_outside_target;
     SimpleEnclosedRegion occlusion_from_inside_target;
+    bool ignores_parent_occlusion = false;
   };
 
   // The stack holds occluded regions for subtrees in the

cc/trees/occlusion_tracker_unittest.cc

@@ -992,6 +992,63 @@ class OcclusionTrackerTestFilters : public OcclusionTrackerTest {
 
 ALL_OCCLUSIONTRACKER_TEST(OcclusionTrackerTestFilters)
 
+class OcclusionTrackerTestFiltersRenderSurfaceOcclusion
+    : public OcclusionTrackerTest {
+ protected:
+  using OcclusionTrackerTest::OcclusionTrackerTest;
+
+  void RunMyTest() override {
+    TestContentLayerImpl* parent = CreateRoot(gfx::Size(500, 500));
+    TestContentLayerImpl* blur_layer = CreateDrawingSurface(
+        parent, gfx::Transform(), gfx::PointF(100.f, 100.f), gfx::Size(50, 50),
+        true);
+    TestContentLayerImpl* opacity_layer = CreateDrawingSurface(
+        parent, gfx::Transform(), gfx::PointF(200.f, 100.f), gfx::Size(50, 50),
+        true);
+
+    // This layer fully covers the layer bounds of the above filtered layers,
+    // but not the blur filter extent of |blur_layer|.
+    TestContentLayerImpl* occluding_layer =
+        CreateDrawingLayer(parent, gfx::Transform(), gfx::PointF(100.f, 100.f),
+                           gfx::Size(300, 100), true);
+
+    FilterOperations filters;
+    filters.Append(FilterOperation::CreateBlurFilter(10.f));
+    GetEffectNode(blur_layer)->filters = filters;
+
+    filters.Clear();
+    filters.Append(FilterOperation::CreateOpacityFilter(0.5f));
+    GetEffectNode(opacity_layer)->filters = filters;
+
+    CalcDrawEtc();
+    TestOcclusionTrackerWithClip occlusion(gfx::Rect(0, 0, 1000, 1000));
+
+    ASSERT_NO_FATAL_FAILURE(VisitLayer(occluding_layer, &occlusion));
+
+    // The render surface of |opacity_layer| (which has a filter that doesn't
+    // move pixels) is occluded by |occluding_layer|.
+    ASSERT_NO_FATAL_FAILURE(VisitLayer(opacity_layer, &occlusion));
+    ASSERT_NO_FATAL_FAILURE(
+        EnterContributingSurface(opacity_layer, &occlusion));
+    EXPECT_EQ(gfx::Rect(),
+              occlusion.UnoccludedSurfaceContentRect(
+                  opacity_layer, gfx::Rect(opacity_layer->bounds())));
+    ASSERT_NO_FATAL_FAILURE(
+        LeaveContributingSurface(opacity_layer, &occlusion));
+
+    // The render surface of |blur_layer| (which has a filter that moves pixels)
+    // is not occluded by |occluding_layer|.
+    ASSERT_NO_FATAL_FAILURE(VisitLayer(blur_layer, &occlusion));
+    ASSERT_NO_FATAL_FAILURE(EnterContributingSurface(blur_layer, &occlusion));
+    EXPECT_EQ(gfx::Rect(blur_layer->bounds()),
+              occlusion.UnoccludedSurfaceContentRect(
+                  blur_layer, gfx::Rect(blur_layer->bounds())));
+    ASSERT_NO_FATAL_FAILURE(LeaveContributingSurface(blur_layer, &occlusion));
+  }
+};
+
+ALL_OCCLUSIONTRACKER_TEST(OcclusionTrackerTestFiltersRenderSurfaceOcclusion)
+
 class OcclusionTrackerTestOpaqueContentsRegionEmpty
     : public OcclusionTrackerTest {
  protected:

third_party/blink/web_tests/FlagExpectations/composite-after-paint

@@ -57,8 +57,6 @@ virtual/android/url-bar/bottom-and-top-fixed-sticks-to-top.html [ Crash ]
 virtual/android/url-bar/bottom-fixed-adjusted-when-showing-url-bar.html [ Crash ]
 
 # Composited filters are not working.
-crbug.com/1008501 compositing/culling/filter-occlusion-blur-large.html [ Failure ]
-crbug.com/1008501 compositing/culling/filter-occlusion-blur.html [ Failure ]
 crbug.com/1008501 compositing/reflections/deeply-nested-reflections.html [ Failure ]
 
 # Wrong contentsOpaque or background color.

third_party/blink/web_tests/compositing/culling/filter-occlusion-blur-large.html

@@ -10,8 +10,6 @@
     will-change: transform;
   }
   .yellow-parent {
-    width: 800px;
-    height:  800px;
     -webkit-filter: blur(10px);
   }
   .centered {

third_party/blink/web_tests/compositing/culling/filter-occlusion-blur.html

@@ -6,8 +6,6 @@
     will-change: transform;
   }
   .yellow-parent {
-    width: 600px;
-    height:  600px;
     -webkit-filter: blur(10px);
   }
   .centered {