[BGPT] Collect graphics layers only when needed

- Call LocalFrameView::SetGraphicsLayersChanged() when graphics layer
  hierarchy changes or any graphics layer changes property tree state
  or offset. The function also sets PaintArtifactCompositorNeedsUpdate.

- Use a long-live paint controller in LocalFrameView to collect
  foreign layers of graphics layers. If graphics layers didn't change,
  just use the previous collected foreign layers.

Change-Id: I0c95b19098807cf0c640d9d26c62e68eb33acec9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600302Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658313}

third_party/blink/renderer/core/frame/local_frame_view.cc

@@ -2474,7 +2474,6 @@ void LocalFrameView::RunPaintLifecyclePhase() {
             }
           });
         }
-        paint_controller_ = nullptr;
       }
     }
   }
@@ -2508,18 +2507,6 @@ void LocalFrameView::PerformScrollAnchoringAdjustments() {
 static void RecordGraphicsLayerAsForeignLayer(
     GraphicsContext& context,
     const GraphicsLayer* graphics_layer) {
-  // Copy the first chunk's safe opaque background color over to the cc::Layer
-  // in the foreign layer wrapper.
-  if (graphics_layer->DrawsContent()) {
-    auto& chunks =
-        graphics_layer->GetPaintController().GetPaintArtifact().PaintChunks();
-    SkColor safe_background_color = SK_ColorWHITE;
-    if (chunks.size()) {
-      safe_background_color = chunks[0].safe_opaque_background_color;
-    }
-    graphics_layer->CcLayer()->SetSafeOpaqueBackgroundColor(
-        safe_background_color);
-  }
   // TODO(trchen): Currently the GraphicsLayer hierarchy is still built during
   // CompositingUpdate, and we have to clear them here to ensure no extraneous
   // layers are still attached. In future we will disable all those layer
@@ -2719,6 +2706,13 @@ void LocalFrameView::PushPaintArtifactToCompositor() {
   SCOPED_UMA_AND_UKM_TIMER(EnsureUkmAggregator(),
                            LocalFrameUkmAggregator::kCompositingCommit);
 
+  // Skip updating property trees, pushing cc::Layers, and issuing raster
+  // invalidations if possible.
+  if (!paint_artifact_compositor_->NeedsUpdate()) {
+    DCHECK(paint_controller_);
+    return;
+  }
+
   PaintArtifactCompositor::ViewportProperties viewport_properties;
   if (GetFrame().IsMainFrame()) {
     const auto& viewport = page->GetVisualViewport();
@@ -2731,17 +2725,14 @@ void LocalFrameView::PushPaintArtifactToCompositor() {
   settings.prefer_compositing_to_lcd_text =
       page->GetSettings().GetPreferCompositingToLCDTextEnabled();
 
-  // Skip updating property trees, pushing cc::Layers, and issuing raster
-  // invalidations if possible.
-  if (!paint_artifact_compositor_->NeedsUpdate())
-    return;
-
   if (RuntimeEnabledFeatures::BlinkGenPropertyTreesEnabled() &&
-      !RuntimeEnabledFeatures::CompositeAfterPaintEnabled()) {
-    // BlinkGenPropertyTrees just needs a transient PaintController to
-    // collect the foreign layers which doesn't need caching. It also
-    // shouldn't affect caching status of DisplayItemClients because it's
-    // FinishCycle() is not synchronized with other PaintControllers.
+      !RuntimeEnabledFeatures::CompositeAfterPaintEnabled() &&
+      !paint_controller_) {
+    // BlinkGenPropertyTrees just needs a transient PaintController to collect
+    // the foreign layers which doesn't need caching. It also shouldn't affect
+    // caching status of DisplayItemClients because it's FinishCycle() is not
+    // synchronized with other PaintControllers. It may live across frame update
+    // until GraphicsLayersDidChange() is called.
     paint_controller_ =
         std::make_unique<PaintController>(PaintController::kTransient);
 
@@ -4000,12 +3991,22 @@ void LocalFrameView::SetIntersectionObservationState(
   intersection_observation_state_ = state;
 }
 
-void LocalFrameView::SetPaintArtifactCompositorNeedsUpdate() const {
+void LocalFrameView::SetPaintArtifactCompositorNeedsUpdate() {
   LocalFrameView* root = GetFrame().LocalFrameRoot().View();
   if (root && root->paint_artifact_compositor_)
     root->paint_artifact_compositor_->SetNeedsUpdate();
 }
 
+void LocalFrameView::GraphicsLayersDidChange() {
+  LocalFrameView* root = GetFrame().LocalFrameRoot().View();
+  if (root) {
+    // We will re-collect GraphicsLayers in PushPaintArtifactsToCompositor().
+    root->paint_controller_ = nullptr;
+    if (root->paint_artifact_compositor_)
+      root->paint_artifact_compositor_->SetNeedsUpdate();
+  }
+}
+
 PaintArtifactCompositor* LocalFrameView::GetPaintArtifactCompositor() const {
   LocalFrameView* root = GetFrame().LocalFrameRoot().View();
   return root ? root->paint_artifact_compositor_.get() : nullptr;

third_party/blink/renderer/core/frame/local_frame_view.h

@@ -205,7 +205,8 @@ class CORE_EXPORT LocalFrameView final
 
   void ForceUpdateViewportIntersections();
 
-  void SetPaintArtifactCompositorNeedsUpdate() const;
+  void SetPaintArtifactCompositorNeedsUpdate();
+  void GraphicsLayersDidChange();
 
   // Marks this frame, and ancestor frames, as needing a mandatory compositing
   // update. This overrides throttling for one frame, up to kCompositingClean.
@@ -938,7 +939,14 @@ class CORE_EXPORT LocalFrameView final
   std::unique_ptr<Vector<ObjectPaintInvalidation>>
       tracked_object_paint_invalidations_;
 
-  // For CompositeAfterPaint only.
+  // For BlinkGenPropertyTrees/CompositeAfterPaint only. It's created lazily
+  // when it's used.
+  // - For BlinkGenPropertyTrees, we use it in PushPaintArtifactToCompositor()
+  //   to collect GraphicsLayers as foreign layers. It's transient, but may live
+  //   across frame updates until GraphicsLayersDidChange() is called.
+  // - For CompositeAfterPaint, we use it in PaintTree() for all paintings of
+  //   the frame tree in PaintTree(). It caches display items and subsequences
+  //   across frame updates and repaints.
   std::unique_ptr<PaintController> paint_controller_;
   std::unique_ptr<PaintArtifactCompositor> paint_artifact_compositor_;
 

third_party/blink/renderer/core/frame/visual_viewport.cc

@@ -1156,9 +1156,9 @@ void VisualViewport::SetOverlayScrollbarsHidden(bool hidden) {
   ScrollableArea::SetScrollbarsHiddenIfOverlay(hidden);
 }
 
-void VisualViewport::SetPaintArtifactCompositorNeedsUpdate() const {
+void VisualViewport::GraphicsLayersDidChange() {
   if (MainFrame() && MainFrame()->View())
-    MainFrame()->View()->SetPaintArtifactCompositorNeedsUpdate();
+    MainFrame()->View()->GraphicsLayersDidChange();
 }
 
 PaintArtifactCompositor* VisualViewport::GetPaintArtifactCompositor() const {

third_party/blink/renderer/core/frame/visual_viewport.h

@@ -295,7 +295,7 @@ class CORE_EXPORT VisualViewport final
                      GraphicsLayerPaintingPhase,
                      const IntRect&) const override;
   void SetOverlayScrollbarsHidden(bool) override;
-  void SetPaintArtifactCompositorNeedsUpdate() const override;
+  void GraphicsLayersDidChange() override;
   String DebugName(const GraphicsLayer*) const override;
 
   const ScrollableArea* GetScrollableAreaForTesting(

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.cc

@@ -3506,10 +3506,10 @@ void CompositedLayerMapping::SetOverlayScrollbarsHidden(bool hidden) {
     scrollable_area->SetScrollbarsHiddenIfOverlay(hidden);
 }
 
-void CompositedLayerMapping::SetPaintArtifactCompositorNeedsUpdate() const {
+void CompositedLayerMapping::GraphicsLayersDidChange() {
   LocalFrameView* frame_view = GetLayoutObject().GetFrameView();
   DCHECK(frame_view);
-  frame_view->SetPaintArtifactCompositorNeedsUpdate();
+  frame_view->GraphicsLayersDidChange();
 }
 
 #if DCHECK_IS_ON()

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.h

@@ -215,7 +215,7 @@ class CORE_EXPORT CompositedLayerMapping final : public GraphicsLayerClient {
   bool ShouldThrottleRendering() const override;
   bool IsTrackingRasterInvalidations() const override;
   void SetOverlayScrollbarsHidden(bool) override;
-  void SetPaintArtifactCompositorNeedsUpdate() const override;
+  void GraphicsLayersDidChange() override;
 
 #if DCHECK_IS_ON()
   void VerifyNotPainting() override;

third_party/blink/renderer/core/paint/link_highlight_impl.cc

@@ -514,8 +514,12 @@ void LinkHighlightImpl::Paint(GraphicsContext& context) {
 
 void LinkHighlightImpl::SetPaintArtifactCompositorNeedsUpdate() {
   DCHECK(node_);
-  if (auto* frame_view = node_->GetDocument().View())
-    frame_view->SetPaintArtifactCompositorNeedsUpdate();
+  if (auto* frame_view = node_->GetDocument().View()) {
+    if (RuntimeEnabledFeatures::CompositeAfterPaintEnabled())
+      frame_view->SetPaintArtifactCompositorNeedsUpdate();
+    else
+      frame_view->GraphicsLayersDidChange();
+  }
 }
 
 }  // namespace blink

third_party/blink/renderer/platform/graphics/graphics_layer.cc

@@ -259,7 +259,7 @@ void GraphicsLayer::RemoveFromParent() {
       !RuntimeEnabledFeatures::CompositeAfterPaintEnabled()) {
     CcLayer()->RemoveFromParent();
   } else {
-    SetPaintArtifactCompositorNeedsUpdate();
+    client_.GraphicsLayersDidChange();
   }
 }
 
@@ -323,10 +323,12 @@ bool GraphicsLayer::Paint(GraphicsContext::DisabledMode disabled_mode) {
     return false;
 #endif
 
-  if (PaintWithoutCommit(disabled_mode))
+  if (PaintWithoutCommit(disabled_mode)) {
     GetPaintController().CommitNewDisplayItems();
-  else if (!needs_check_raster_invalidation_)
+    UpdateSafeOpaqueBackgroundColor();
+  } else if (!needs_check_raster_invalidation_) {
     return false;
+  }
 
 #if DCHECK_IS_ON()
   if (VLOG_IS_ON(2)) {
@@ -360,6 +362,15 @@ bool GraphicsLayer::Paint(GraphicsContext::DisabledMode disabled_mode) {
   return true;
 }
 
+void GraphicsLayer::UpdateSafeOpaqueBackgroundColor() {
+  if (!DrawsContent())
+    return;
+  // Copy the first chunk's safe opaque background color over to the cc::Layer.
+  const auto& chunks = GetPaintController().GetPaintArtifact().PaintChunks();
+  CcLayer()->SetSafeOpaqueBackgroundColor(
+      chunks.size() ? chunks[0].safe_opaque_background_color : SK_ColorWHITE);
+}
+
 bool GraphicsLayer::PaintWithoutCommitForTesting(
     const base::Optional<IntRect>& interest_rect) {
   return PaintWithoutCommit(GraphicsContext::kNothingDisabled,
@@ -403,7 +414,7 @@ void GraphicsLayer::UpdateChildList() {
   // When using layer lists, cc::Layers are created in PaintArtifactCompositor.
   if (RuntimeEnabledFeatures::BlinkGenPropertyTreesEnabled() ||
       RuntimeEnabledFeatures::CompositeAfterPaintEnabled()) {
-    SetPaintArtifactCompositorNeedsUpdate();
+    client_.GraphicsLayersDidChange();
     return;
   }
 
@@ -740,10 +751,6 @@ void GraphicsLayer::SetContentsVisible(bool contents_visible) {
   UpdateLayerIsDrawable();
 }
 
-void GraphicsLayer::SetPaintArtifactCompositorNeedsUpdate() const {
-  client_.SetPaintArtifactCompositorNeedsUpdate();
-}
-
 void GraphicsLayer::SetClipParent(cc::Layer* parent) {
   has_clip_parent_ = !!parent;
   CcLayer()->SetClipParent(parent);
@@ -876,6 +883,7 @@ void GraphicsLayer::SetContentsRect(const IntRect& rect) {
 
   contents_rect_ = rect;
   UpdateContentsRect();
+  client_.GraphicsLayersDidChange();
 }
 
 void GraphicsLayer::SetContentsToImage(
@@ -1055,7 +1063,7 @@ void GraphicsLayer::SetLayerState(const PropertyTreeState& layer_state,
   }
 
   if (RuntimeEnabledFeatures::BlinkGenPropertyTreesEnabled())
-    SetPaintArtifactCompositorNeedsUpdate();
+    client_.GraphicsLayersDidChange();
 }
 
 void GraphicsLayer::SetContentsPropertyTreeState(
@@ -1063,11 +1071,15 @@ void GraphicsLayer::SetContentsPropertyTreeState(
   DCHECK(ContentsLayer());
 
   if (contents_property_tree_state_) {
+    if (*contents_property_tree_state_ == layer_state)
+      return;
     *contents_property_tree_state_ = layer_state;
   } else {
     contents_property_tree_state_ =
         std::make_unique<PropertyTreeState>(layer_state);
   }
+  if (RuntimeEnabledFeatures::BlinkGenPropertyTreesEnabled())
+    client_.GraphicsLayersDidChange();
 }
 
 scoped_refptr<cc::DisplayItemList> GraphicsLayer::PaintContentsToDisplayList(

third_party/blink/renderer/platform/graphics/graphics_layer.h

@@ -171,8 +171,6 @@ class PLATFORM_EXPORT GraphicsLayer : public cc::LayerClient,
   void SetScrollParent(cc::Layer*);
   void SetClipParent(cc::Layer*);
 
-  void SetPaintArtifactCompositorNeedsUpdate() const;
-
   // For special cases, e.g. drawing missing tiles on Android.
   // The compositor should never paint this color in normal cases because the
   // Layer will paint the background by itself.
@@ -333,6 +331,7 @@ class PLATFORM_EXPORT GraphicsLayer : public cc::LayerClient,
   size_t GetApproximateUnsharedMemoryUsage() const final;
 
   void PaintRecursivelyInternal(Vector<GraphicsLayer*>& repainted_layers);
+  void UpdateSafeOpaqueBackgroundColor();
 
   // Returns true if PaintController::PaintArtifact() changed and needs commit.
   bool PaintWithoutCommit(

third_party/blink/renderer/platform/graphics/graphics_layer_client.h

@@ -96,7 +96,7 @@ class PLATFORM_EXPORT GraphicsLayerClient {
 
   virtual void SetOverlayScrollbarsHidden(bool) {}
 
-  virtual void SetPaintArtifactCompositorNeedsUpdate() const {}
+  virtual void GraphicsLayersDidChange() {}
 
   virtual String DebugName(const GraphicsLayer*) const = 0;