Skip cc::DisplayItemList conversion from paint chunks if nothing changed

Only convert paint chunks if the layer bounds changed, we have
invalidated raster or we are checking raster under-invalidation.
Otherwise just keep the existing cc::DisplayItemList.

Change-Id: I9ee584344ede6df8fb88af64b4347460389142e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363643Reviewed-by: Stefan Zager <szager@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799648}

third_party/blink/renderer/platform/graphics/compositing/content_layer_client_impl.cc

@@ -88,10 +88,22 @@ scoped_refptr<cc::PictureLayer> ContentLayerClientImpl::UpdateCcPictureLayer(
   if (layer_state != layer_state_)
     cc_picture_layer_->SetSubtreePropertyChanged();
 
+  raster_invalidated_ = false;
+  gfx::Size old_layer_size = raster_invalidator_.LayerBounds().size();
+  DCHECK_EQ(old_layer_size, cc_picture_layer_->bounds());
   raster_invalidator_.Generate(raster_invalidation_function_, paint_artifact,
                                paint_chunks, layer_bounds, layer_state);
   layer_state_ = layer_state;
 
+  base::Optional<RasterUnderInvalidationCheckingParams>
+      raster_under_invalidation_params;
+  if (RuntimeEnabledFeatures::PaintUnderInvalidationCheckingEnabled()) {
+    raster_under_invalidation_params.emplace(
+        *raster_invalidator_.GetTracking(),
+        IntRect(0, 0, layer_bounds.width(), layer_bounds.height()),
+        paint_chunks[0].id.client.DebugName());
+  }
+
   // Note: cc::Layer API assumes the layer bounds start at (0, 0), but the
   // bounding box of a paint chunk does not necessarily start at (0, 0) (and
   // could even be negative). Internally the generated layer translates the
@@ -99,20 +111,23 @@ scoped_refptr<cc::PictureLayer> ContentLayerClientImpl::UpdateCcPictureLayer(
   // offset_to_transform_parent with the origin of the paint chunk here.
   cc_picture_layer_->SetOffsetToTransformParent(
       layer_bounds.OffsetFromOrigin());
-  cc_picture_layer_->SetBounds(layer_bounds.size());
-  cc_picture_layer_->SetHitTestable(true);
 
-  base::Optional<RasterUnderInvalidationCheckingParams> params;
-  if (RuntimeEnabledFeatures::PaintUnderInvalidationCheckingEnabled()) {
-    params.emplace(*raster_invalidator_.GetTracking(),
-                   IntRect(0, 0, layer_bounds.width(), layer_bounds.height()),
-                   paint_chunks[0].id.client.DebugName());
+  // If nothing changed in the layer, keep the original display item list.
+  // Here check layer_bounds because RasterInvalidator doesn't issue raster
+  // invalidation when layer_bounds become empty or non-empty from empty.
+  if (layer_bounds.size() == old_layer_size && !raster_invalidated_ &&
+      !raster_under_invalidation_params && cc_display_item_list_) {
+    DCHECK_EQ(cc_picture_layer_->bounds(), layer_bounds.size());
+    return cc_picture_layer_;
   }
+
   cc_display_item_list_ = PaintChunksToCcLayer::Convert(
       paint_chunks, layer_state, layer_bounds.OffsetFromOrigin(),
       display_item_list, cc::DisplayItemList::kTopLevelDisplayItemList,
-      base::OptionalOrNullptr(params));
+      base::OptionalOrNullptr(raster_under_invalidation_params));
 
+  cc_picture_layer_->SetBounds(layer_bounds.size());
+  cc_picture_layer_->SetHitTestable(true);
   cc_picture_layer_->SetIsDrawable(
       (!layer_bounds.IsEmpty() && cc_display_item_list_->TotalOpCount()) ||
       // Backdrop effects and filters require the layer to be drawable even if

third_party/blink/renderer/platform/graphics/compositing/content_layer_client_impl.h

@@ -67,6 +67,7 @@ class PLATFORM_EXPORT ContentLayerClientImpl : public cc::ContentLayerClient,
  private:
   // Callback from raster_invalidator_.
   void InvalidateRect(const IntRect& rect) {
+    raster_invalidated_ = true;
     cc_picture_layer_->SetNeedsDisplayRect(rect);
   }
 
@@ -75,6 +76,7 @@ class PLATFORM_EXPORT ContentLayerClientImpl : public cc::ContentLayerClient,
   scoped_refptr<cc::DisplayItemList> cc_display_item_list_;
   RasterInvalidator raster_invalidator_;
   RasterInvalidator::RasterInvalidationFunction raster_invalidation_function_;
+  bool raster_invalidated_ = false;
 
   PropertyTreeState layer_state_;
 

third_party/blink/renderer/platform/graphics/compositing/paint_artifact_compositor_test.cc

@@ -4856,13 +4856,17 @@ TEST_P(PaintArtifactCompositorTest, TransformChange) {
   t2_state.direct_compositing_reasons = CompositingReason::k3DTransform;
   auto t2 = TransformPaintPropertyNode::Create(*t1, std::move(t2_state));
 
+  FakeDisplayItemClient client;
+  client.Validate();
   Update(TestPaintArtifact()
              .Chunk(1)
              .Properties(*t2, c0(), e0())
-             .RectDrawing(IntRect(100, 100, 200, 100), Color::kBlack)
+             .RectDrawing(client, IntRect(100, 100, 200, 100), Color::kBlack)
              .Build());
   ASSERT_EQ(1u, LayerCount());
-  cc::Layer* layer = LayerAt(0);
+  auto* layer = static_cast<cc::PictureLayer*>(LayerAt(0));
+  auto display_item_list = layer->client()->PaintContentsToDisplayList(
+      cc::ContentLayerClient::PAINTING_BEHAVIOR_NORMAL);
 
   // Change t1 but not t2.
   layer->ClearSubtreePropertyChangedForTesting();
@@ -4874,11 +4878,16 @@ TEST_P(PaintArtifactCompositorTest, TransformChange) {
   Update(TestPaintArtifact()
              .Chunk(1)
              .Properties(*t2, c0(), e0())
-             .RectDrawing(IntRect(100, 100, 200, 100), Color::kBlack)
+             .RectDrawing(client, IntRect(100, 100, 200, 100), Color::kBlack)
              .Build());
 
   ASSERT_EQ(1u, LayerCount());
   ASSERT_EQ(layer, LayerAt(0));
+  EXPECT_EQ(display_item_list.get(),
+            layer->client()
+                ->PaintContentsToDisplayList(
+                    cc::ContentLayerClient::PAINTING_BEHAVIOR_NORMAL)
+                .get());
   // TODO(wangxianzhu): Probably avoid setting this flag on transform change.
   EXPECT_TRUE(layer->subtree_property_changed());
   // This is set by cc when propagating ancestor change flag to descendants.
@@ -4899,11 +4908,16 @@ TEST_P(PaintArtifactCompositorTest, TransformChange) {
   Update(TestPaintArtifact()
              .Chunk(1)
              .Properties(*t2, c0(), e0())
-             .RectDrawing(IntRect(100, 100, 200, 100), Color::kBlack)
+             .RectDrawing(client, IntRect(100, 100, 200, 100), Color::kBlack)
              .Build());
 
   ASSERT_EQ(1u, LayerCount());
   ASSERT_EQ(layer, LayerAt(0));
+  EXPECT_EQ(display_item_list.get(),
+            layer->client()
+                ->PaintContentsToDisplayList(
+                    cc::ContentLayerClient::PAINTING_BEHAVIOR_NORMAL)
+                .get());
   // TODO(wangxianzhu): Probably avoid setting this flag on transform change.
   EXPECT_TRUE(layer->subtree_property_changed());
   EXPECT_TRUE(GetTransformNode(layer).transform_changed);
@@ -4921,16 +4935,39 @@ TEST_P(PaintArtifactCompositorTest, TransformChange) {
   Update(TestPaintArtifact()
              .Chunk(1)
              .Properties(*t2, c0(), e0())
-             .RectDrawing(IntRect(100, 100, 200, 100), Color::kBlack)
+             .RectDrawing(client, IntRect(100, 100, 200, 100), Color::kBlack)
              .Build());
 
   ASSERT_EQ(1u, LayerCount());
   ASSERT_EQ(layer, LayerAt(0));
+  EXPECT_EQ(display_item_list.get(),
+            layer->client()
+                ->PaintContentsToDisplayList(
+                    cc::ContentLayerClient::PAINTING_BEHAVIOR_NORMAL)
+                .get());
   // The new transform is decomposited, so there is no transform_changed, but
   // we set subtree_property_changed because offset_from_transform_parent
   // (calculated from the decomposited transforms) changed.
   EXPECT_TRUE(layer->subtree_property_changed());
   EXPECT_FALSE(GetTransformNode(layer).transform_changed);
+
+  // Change no transform nodes, but invalidate client.
+  layer->ClearSubtreePropertyChangedForTesting();
+  t2->ClearChangedToRoot();
+  client.Invalidate(PaintInvalidationReason::kBackground);
+  Update(TestPaintArtifact()
+             .Chunk(1)
+             .Properties(*t2, c0(), e0())
+             .RectDrawing(client, IntRect(100, 100, 200, 100), Color::kWhite)
+             .Build());
+
+  ASSERT_EQ(1u, LayerCount());
+  ASSERT_EQ(layer, LayerAt(0));
+  EXPECT_NE(display_item_list.get(),
+            layer->client()
+                ->PaintContentsToDisplayList(
+                    cc::ContentLayerClient::PAINTING_BEHAVIOR_NORMAL)
+                .get());
 }
 
 TEST_P(PaintArtifactCompositorTest, EffectChange) {