Set filter bounds to empty rect if the content is empty

Previously if a filter has empty content, the bounds of the SaveLayerOp
was left unset, causing bad performance in pdf renderer. Now set the
bounds to an empty rect.

Bug: 918240, 1050694
Change-Id: I7d39336c9525a32af88dac29dc2eb0dc38cd067f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2047380Reviewed-by: vmpstr <vmpstr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740824}

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

@@ -618,20 +618,20 @@ void ConversionContext::EndEffect() {
   DCHECK(effect_bounds_stack_.size());
   const auto& bounds_info = effect_bounds_stack_.back();
   FloatRect bounds = bounds_info.bounds;
-  if (!bounds.IsEmpty()) {
-    if (current_effect_->Filter().IsEmpty()) {
+  if (current_effect_->Filter().IsEmpty()) {
+    if (!bounds.IsEmpty())
       cc_list_.UpdateSaveLayerBounds(bounds_info.save_layer_id, bounds);
-    } else {
-      // The bounds for the SaveLayer[Alpha]Op should be the source bounds
-      // before the filter is applied, in the space of the TranslateOp which was
-      // emitted before the SaveLayer[Alpha]Op.
-      auto save_layer_bounds = bounds;
+  } else {
+    // The bounds for the SaveLayer[Alpha]Op should be the source bounds
+    // before the filter is applied, in the space of the TranslateOp which was
+    // emitted before the SaveLayer[Alpha]Op.
+    auto save_layer_bounds = bounds;
+    if (!save_layer_bounds.IsEmpty())
       save_layer_bounds.MoveBy(-current_effect_->FiltersOrigin());
-      cc_list_.UpdateSaveLayerBounds(bounds_info.save_layer_id,
-                                     save_layer_bounds);
-      // We need to propagate the filtered bounds to the parent.
-      bounds = current_effect_->MapRect(bounds);
-    }
+    cc_list_.UpdateSaveLayerBounds(bounds_info.save_layer_id,
+                                   save_layer_bounds);
+    // We need to propagate the filtered bounds to the parent.
+    bounds = current_effect_->MapRect(bounds);
   }
 
   effect_bounds_stack_.pop_back();

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

@@ -1313,5 +1313,23 @@ TEST_P(PaintChunksToCcLayerTest, AllowChunkEscapeLayerNoopEffects) {
                        }));
 }
 
+TEST_P(PaintChunksToCcLayerTest, EmptyChunkRect) {
+  CompositorFilterOperations filter;
+  filter.AppendBlurFilter(5);
+  auto e1 = CreateFilterEffect(e0(), t0(), &c0(), filter, FloatPoint(0, 0));
+  TestChunks chunks;
+  chunks.AddChunk(nullptr, t0(), c0(), *e1, {0, 0, 0, 0});
+
+  auto output =
+      PaintChunksToCcLayer::Convert(
+          chunks.chunks, PropertyTreeState::Root(), gfx::Vector2dF(),
+          chunks.items, cc::DisplayItemList::kToBeReleasedAsPaintOpBuffer)
+          ->ReleaseAsRecord();
+  EXPECT_THAT(*output,
+              PaintRecordMatcher::Make({cc::PaintOpType::SaveLayer,   // <e1>
+                                        cc::PaintOpType::Restore}));  // </e1>
+  EXPECT_EFFECT_BOUNDS(0, 0, 0, 0, *output, 0);
+}
+
 }  // namespace
 }  // namespace blink