Make flow::LayerBuilder virtual and plug in the default layer builder. (flutter/engine#4199)

engine/src/flutter/flow/BUILD.gn

@@ -22,6 +22,8 @@ source_set("flow") {
     "layers/color_filter_layer.h",
     "layers/container_layer.cc",
     "layers/container_layer.h",
+    "layers/default_layer_builder.cc",
+    "layers/default_layer_builder.h",
     "layers/layer.cc",
     "layers/layer.h",
     "layers/layer_builder.cc",

engine/src/flutter/flow/debug_print.cc

@@ -59,6 +59,12 @@ std::ostream& operator<<(std::ostream& os, const SkRect& r) {
   return os;
 }
 
+std::ostream& operator<<(std::ostream& os, const SkRRect& r) {
+  os << "LTRB: " << r.rect().fLeft << ", " << r.rect().fTop << ", "
+     << r.rect().fRight << ", " << r.rect().fBottom;
+  return os;
+}
+
 std::ostream& operator<<(std::ostream& os, const SkPoint& r) {
   os << "XY: " << r.fX << ", " << r.fY;
   return os;

engine/src/flutter/flow/debug_print.h

@@ -11,6 +11,7 @@
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkMatrix44.h"
 #include "third_party/skia/include/core/SkPoint3.h"
+#include "third_party/skia/include/core/SkRRect.h"
 
 #define DEF_PRINTER(x) std::ostream& operator<<(std::ostream&, const x&);
 
@@ -21,6 +22,7 @@ DEF_PRINTER(SkMatrix44);
 DEF_PRINTER(SkVector3);
 DEF_PRINTER(SkVector4);
 DEF_PRINTER(SkRect);
+DEF_PRINTER(SkRRect);
 DEF_PRINTER(SkPoint);
 
 #endif  // FLUTTER_FLOW_DEBUG_PRINT_H_

engine/src/flutter/flow/layers/default_layer_builder.cc

@@ -0,0 +1,210 @@
+// Copyright 2017 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/flow/layers/default_layer_builder.h"
+
+#include "flutter/flow/layers/backdrop_filter_layer.h"
+#include "flutter/flow/layers/clip_path_layer.h"
+#include "flutter/flow/layers/clip_rect_layer.h"
+#include "flutter/flow/layers/clip_rrect_layer.h"
+#include "flutter/flow/layers/color_filter_layer.h"
+#include "flutter/flow/layers/container_layer.h"
+#include "flutter/flow/layers/layer.h"
+#include "flutter/flow/layers/layer_tree.h"
+#include "flutter/flow/layers/opacity_layer.h"
+#include "flutter/flow/layers/performance_overlay_layer.h"
+#include "flutter/flow/layers/physical_model_layer.h"
+#include "flutter/flow/layers/picture_layer.h"
+#include "flutter/flow/layers/shader_mask_layer.h"
+#include "flutter/flow/layers/transform_layer.h"
+
+#if defined(OS_FUCHSIA)
+#include "flutter/flow/layers/child_scene_layer.h"
+#endif  // defined(OS_FUCHSIA)
+
+namespace flow {
+
+DefaultLayerBuilder::DefaultLayerBuilder() {
+  cull_rects_.push(SkRect::MakeLargest());
+}
+
+DefaultLayerBuilder::~DefaultLayerBuilder() = default;
+
+void DefaultLayerBuilder::PushTransform(const SkMatrix& sk_matrix) {
+  SkMatrix inverse_sk_matrix;
+  SkRect cullRect;
+  if (sk_matrix.invert(&inverse_sk_matrix)) {
+    inverse_sk_matrix.mapRect(&cullRect, cull_rects_.top());
+  } else {
+    cullRect = SkRect::MakeLargest();
+  }
+
+  auto layer = std::make_unique<flow::TransformLayer>();
+  layer->set_transform(sk_matrix);
+  PushLayer(std::move(layer), cullRect);
+}
+
+void DefaultLayerBuilder::PushClipRect(const SkRect& clipRect) {
+  SkRect cullRect;
+  if (!cullRect.intersect(clipRect, cull_rects_.top())) {
+    cullRect = SkRect::MakeEmpty();
+  }
+  auto layer = std::make_unique<flow::ClipRectLayer>();
+  layer->set_clip_rect(clipRect);
+  PushLayer(std::move(layer), cullRect);
+}
+
+void DefaultLayerBuilder::PushClipRoundedRect(const SkRRect& rrect) {
+  SkRect cullRect;
+  if (!cullRect.intersect(rrect.rect(), cull_rects_.top())) {
+    cullRect = SkRect::MakeEmpty();
+  }
+  auto layer = std::make_unique<flow::ClipRRectLayer>();
+  layer->set_clip_rrect(rrect);
+  PushLayer(std::move(layer), cullRect);
+}
+
+void DefaultLayerBuilder::PushClipPath(const SkPath& path) {
+  SkRect cullRect;
+  if (!cullRect.intersect(path.getBounds(), cull_rects_.top())) {
+    cullRect = SkRect::MakeEmpty();
+  }
+  auto layer = std::make_unique<flow::ClipPathLayer>();
+  layer->set_clip_path(path);
+  PushLayer(std::move(layer), cullRect);
+}
+
+void DefaultLayerBuilder::PushOpacity(int alpha) {
+  auto layer = std::make_unique<flow::OpacityLayer>();
+  layer->set_alpha(alpha);
+  PushLayer(std::move(layer), cull_rects_.top());
+}
+
+void DefaultLayerBuilder::PushColorFilter(SkColor color,
+                                          SkBlendMode blend_mode) {
+  auto layer = std::make_unique<flow::ColorFilterLayer>();
+  layer->set_color(color);
+  layer->set_blend_mode(blend_mode);
+  PushLayer(std::move(layer), cull_rects_.top());
+}
+
+void DefaultLayerBuilder::PushBackdropFilter(sk_sp<SkImageFilter> filter) {
+  auto layer = std::make_unique<flow::BackdropFilterLayer>();
+  layer->set_filter(filter);
+  PushLayer(std::move(layer), cull_rects_.top());
+}
+
+void DefaultLayerBuilder::PushShaderMask(sk_sp<SkShader> shader,
+                                         const SkRect& rect,
+                                         SkBlendMode blend_mode) {
+  auto layer = std::make_unique<flow::ShaderMaskLayer>();
+  layer->set_shader(shader);
+  layer->set_mask_rect(rect);
+  layer->set_blend_mode(blend_mode);
+  PushLayer(std::move(layer), cull_rects_.top());
+}
+
+void DefaultLayerBuilder::PushPhysicalModel(const SkRRect& sk_rrect,
+                                            double elevation,
+                                            SkColor color,
+                                            SkScalar device_pixel_ratio) {
+  SkRect cullRect;
+  if (!cullRect.intersect(sk_rrect.rect(), cull_rects_.top())) {
+    cullRect = SkRect::MakeEmpty();
+  }
+  auto layer = std::make_unique<flow::PhysicalModelLayer>();
+  layer->set_rrect(sk_rrect);
+  layer->set_elevation(elevation);
+  layer->set_color(color);
+  layer->set_device_pixel_ratio(device_pixel_ratio);
+  PushLayer(std::move(layer), cullRect);
+}
+
+void DefaultLayerBuilder::PushPerformanceOverlay(uint64_t enabled_options,
+                                                 const SkRect& rect) {
+  if (!current_layer_) {
+    return;
+  }
+  auto layer = std::make_unique<flow::PerformanceOverlayLayer>(enabled_options);
+  layer->set_paint_bounds(rect);
+  current_layer_->Add(std::move(layer));
+}
+
+void DefaultLayerBuilder::PushPicture(const SkPoint& offset,
+                                      sk_sp<SkPicture> picture,
+                                      bool picture_is_complex,
+                                      bool picture_will_change) {
+  if (!current_layer_) {
+    return;
+  }
+  SkRect pictureRect = picture->cullRect();
+  pictureRect.offset(offset.x(), offset.y());
+  if (!SkRect::Intersects(pictureRect, cull_rects_.top())) {
+    return;
+  }
+  auto layer = std::make_unique<flow::PictureLayer>();
+  layer->set_offset(offset);
+  layer->set_picture(picture);
+  layer->set_is_complex(picture_is_complex);
+  layer->set_will_change(picture_will_change);
+  current_layer_->Add(std::move(layer));
+}
+
+#if defined(OS_FUCHSIA)
+void DefaultLayerBuilder::PushChildScene(
+    const SkPoint& offset,
+    const SkSize& size,
+    fxl::RefPtr<flow::ExportNodeHolder> export_token_holder,
+    bool hit_testable) {
+  if (!current_layer_) {
+    return;
+  }
+  SkRect sceneRect =
+      SkRect::MakeXYWH(offset.x(), offset.y(), size.width(), size.height());
+  if (!SkRect::Intersects(sceneRect, cull_rects_.top())) {
+    return;
+  }
+  auto layer = std::make_unique<flow::ChildSceneLayer>();
+  layer->set_offset(offset);
+  layer->set_size(size);
+  layer->set_export_node_holder(std::move(export_token_holder));
+  layer->set_hit_testable(hit_testable);
+  current_layer_->Add(std::move(layer));
+}
+#endif  // defined(OS_FUCHSIA)
+
+void DefaultLayerBuilder::Pop() {
+  if (!current_layer_) {
+    return;
+  }
+  cull_rects_.pop();
+  current_layer_ = current_layer_->parent();
+}
+
+std::unique_ptr<flow::Layer> DefaultLayerBuilder::TakeLayer() {
+  return std::move(root_layer_);
+}
+
+void DefaultLayerBuilder::PushLayer(std::unique_ptr<flow::ContainerLayer> layer,
+                                    const SkRect& cullRect) {
+  FXL_DCHECK(layer);
+
+  cull_rects_.push(cullRect);
+
+  if (!root_layer_) {
+    root_layer_ = std::move(layer);
+    current_layer_ = root_layer_.get();
+    return;
+  }
+
+  if (!current_layer_) {
+    return;
+  }
+
+  flow::ContainerLayer* newLayer = layer.get();
+  current_layer_->Add(std::move(layer));
+  current_layer_ = newLayer;
+}
+
+}  // namespace flow

engine/src/flutter/flow/layers/default_layer_builder.h

@@ -0,0 +1,93 @@
+// Copyright 2017 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_FLOW_LAYERS_DEFAULT_LAYER_BUILDER_H_
+#define FLUTTER_FLOW_LAYERS_DEFAULT_LAYER_BUILDER_H_
+
+#include <stack>
+
+#include "flutter/flow/layers/container_layer.h"
+#include "flutter/flow/layers/layer_builder.h"
+#include "garnet/public/lib/fxl/macros.h"
+
+namespace flow {
+
+class DefaultLayerBuilder final : public LayerBuilder {
+ public:
+  DefaultLayerBuilder();
+
+  // |flow::LayerBuilder|
+  ~DefaultLayerBuilder() override;
+
+  // |flow::LayerBuilder|
+  void PushTransform(const SkMatrix& matrix) override;
+
+  // |flow::LayerBuilder|
+  void PushClipRect(const SkRect& rect) override;
+
+  // |flow::LayerBuilder|
+  void PushClipRoundedRect(const SkRRect& rect) override;
+
+  // |flow::LayerBuilder|
+  void PushClipPath(const SkPath& path) override;
+
+  // |flow::LayerBuilder|
+  void PushOpacity(int alpha) override;
+
+  // |flow::LayerBuilder|
+  void PushColorFilter(SkColor color, SkBlendMode blend_mode) override;
+
+  // |flow::LayerBuilder|
+  void PushBackdropFilter(sk_sp<SkImageFilter> filter) override;
+
+  // |flow::LayerBuilder|
+  void PushShaderMask(sk_sp<SkShader> shader,
+                      const SkRect& rect,
+                      SkBlendMode blend_mode) override;
+
+  // |flow::LayerBuilder|
+  void PushPhysicalModel(const SkRRect& rect,
+                         double elevation,
+                         SkColor color,
+                         SkScalar device_pixel_ratio) override;
+
+  // |flow::LayerBuilder|
+  void PushPerformanceOverlay(uint64_t enabled_options,
+                              const SkRect& rect) override;
+
+  // |flow::LayerBuilder|
+  void PushPicture(const SkPoint& offset,
+                   sk_sp<SkPicture> picture,
+                   bool picture_is_complex,
+                   bool picture_will_change) override;
+
+#if defined(OS_FUCHSIA)
+  // |flow::LayerBuilder|
+  void PushChildScene(const SkPoint& offset,
+                      const SkSize& size,
+                      fxl::RefPtr<flow::ExportNodeHolder> export_token_holder,
+                      bool hit_testable) override;
+#endif  // defined(OS_FUCHSIA)
+
+  // |flow::LayerBuilder|
+  void Pop() override;
+
+  // |flow::LayerBuilder|
+  std::unique_ptr<flow::Layer> TakeLayer() override;
+
+ private:
+  std::unique_ptr<flow::ContainerLayer> root_layer_;
+  flow::ContainerLayer* current_layer_ = nullptr;
+
+  std::stack<SkRect> cull_rects_;
+
+  void PushLayer(std::unique_ptr<flow::ContainerLayer> layer,
+                 const SkRect& cullRect);
+
+  FXL_DISALLOW_COPY_AND_ASSIGN(DefaultLayerBuilder);
+};
+
+}  // namespace flow
+
+#endif  // FLUTTER_FLOW_LAYERS_DEFAULT_LAYER_BUILDER_H_

engine/src/flutter/flow/layers/layer_builder.cc

@@ -3,184 +3,18 @@
 // found in the LICENSE file.
 
 #include "flutter/flow/layers/layer_builder.h"
-
-#include "flutter/flow/layers/backdrop_filter_layer.h"
-#include "flutter/flow/layers/clip_path_layer.h"
-#include "flutter/flow/layers/clip_rect_layer.h"
-#include "flutter/flow/layers/clip_rrect_layer.h"
-#include "flutter/flow/layers/color_filter_layer.h"
-#include "flutter/flow/layers/container_layer.h"
-#include "flutter/flow/layers/layer.h"
-#include "flutter/flow/layers/layer_tree.h"
-#include "flutter/flow/layers/opacity_layer.h"
-#include "flutter/flow/layers/performance_overlay_layer.h"
-#include "flutter/flow/layers/physical_model_layer.h"
-#include "flutter/flow/layers/picture_layer.h"
-#include "flutter/flow/layers/shader_mask_layer.h"
-#include "flutter/flow/layers/transform_layer.h"
-
-#if defined(OS_FUCHSIA)
-#include "flutter/flow/layers/child_scene_layer.h"
-#endif  // defined(OS_FUCHSIA)
+#include "flutter/flow/layers/default_layer_builder.h"
 
 namespace flow {
 
-LayerBuilder::LayerBuilder() {
-  cull_rects_.push(SkRect::MakeLargest());
+std::unique_ptr<LayerBuilder> LayerBuilder::Create() {
+  return std::make_unique<DefaultLayerBuilder>();
 }
 
+LayerBuilder::LayerBuilder() = default;
+
 LayerBuilder::~LayerBuilder() = default;
 
-void LayerBuilder::PushTransform(const SkMatrix& sk_matrix) {
-  SkMatrix inverse_sk_matrix;
-  SkRect cullRect;
-  if (sk_matrix.invert(&inverse_sk_matrix)) {
-    inverse_sk_matrix.mapRect(&cullRect, cull_rects_.top());
-  } else {
-    cullRect = SkRect::MakeLargest();
-  }
-
-  auto layer = std::make_unique<flow::TransformLayer>();
-  layer->set_transform(sk_matrix);
-  PushLayer(std::move(layer), cullRect);
-}
-
-void LayerBuilder::PushClipRect(const SkRect& clipRect) {
-  SkRect cullRect;
-  if (!cullRect.intersect(clipRect, cull_rects_.top())) {
-    cullRect = SkRect::MakeEmpty();
-  }
-  auto layer = std::make_unique<flow::ClipRectLayer>();
-  layer->set_clip_rect(clipRect);
-  PushLayer(std::move(layer), cullRect);
-}
-
-void LayerBuilder::PushClipRoundedRect(const SkRRect& rrect) {
-  SkRect cullRect;
-  if (!cullRect.intersect(rrect.rect(), cull_rects_.top())) {
-    cullRect = SkRect::MakeEmpty();
-  }
-  auto layer = std::make_unique<flow::ClipRRectLayer>();
-  layer->set_clip_rrect(rrect);
-  PushLayer(std::move(layer), cullRect);
-}
-
-void LayerBuilder::PushClipPath(const SkPath& path) {
-  SkRect cullRect;
-  if (!cullRect.intersect(path.getBounds(), cull_rects_.top())) {
-    cullRect = SkRect::MakeEmpty();
-  }
-  auto layer = std::make_unique<flow::ClipPathLayer>();
-  layer->set_clip_path(path);
-  PushLayer(std::move(layer), cullRect);
-}
-
-void LayerBuilder::PushOpacity(int alpha) {
-  auto layer = std::make_unique<flow::OpacityLayer>();
-  layer->set_alpha(alpha);
-  PushLayer(std::move(layer), cull_rects_.top());
-}
-
-void LayerBuilder::PushColorFilter(SkColor color, SkBlendMode blend_mode) {
-  auto layer = std::make_unique<flow::ColorFilterLayer>();
-  layer->set_color(color);
-  layer->set_blend_mode(blend_mode);
-  PushLayer(std::move(layer), cull_rects_.top());
-}
-
-void LayerBuilder::PushBackdropFilter(sk_sp<SkImageFilter> filter) {
-  auto layer = std::make_unique<flow::BackdropFilterLayer>();
-  layer->set_filter(filter);
-  PushLayer(std::move(layer), cull_rects_.top());
-}
-
-void LayerBuilder::PushShaderMask(sk_sp<SkShader> shader,
-                                  const SkRect& rect,
-                                  SkBlendMode blend_mode) {
-  auto layer = std::make_unique<flow::ShaderMaskLayer>();
-  layer->set_shader(shader);
-  layer->set_mask_rect(rect);
-  layer->set_blend_mode(blend_mode);
-  PushLayer(std::move(layer), cull_rects_.top());
-}
-
-void LayerBuilder::PushPhysicalModel(const SkRRect& sk_rrect,
-                                     double elevation,
-                                     SkColor color,
-                                     SkScalar device_pixel_ratio) {
-  SkRect cullRect;
-  if (!cullRect.intersect(sk_rrect.rect(), cull_rects_.top())) {
-    cullRect = SkRect::MakeEmpty();
-  }
-  auto layer = std::make_unique<flow::PhysicalModelLayer>();
-  layer->set_rrect(sk_rrect);
-  layer->set_elevation(elevation);
-  layer->set_color(color);
-  layer->set_device_pixel_ratio(device_pixel_ratio);
-  PushLayer(std::move(layer), cullRect);
-}
-
-void LayerBuilder::PushPerformanceOverlay(uint64_t enabled_options,
-                                          const SkRect& rect) {
-  if (!current_layer_) {
-    return;
-  }
-  auto layer = std::make_unique<flow::PerformanceOverlayLayer>(enabled_options);
-  layer->set_paint_bounds(rect);
-  current_layer_->Add(std::move(layer));
-}
-
-void LayerBuilder::PushPicture(const SkPoint& offset,
-                               sk_sp<SkPicture> picture,
-                               bool picture_is_complex,
-                               bool picture_will_change) {
-  if (!current_layer_) {
-    return;
-  }
-  SkRect pictureRect = picture->cullRect();
-  pictureRect.offset(offset.x(), offset.y());
-  if (!SkRect::Intersects(pictureRect, cull_rects_.top())) {
-    return;
-  }
-  auto layer = std::make_unique<flow::PictureLayer>();
-  layer->set_offset(offset);
-  layer->set_picture(picture);
-  layer->set_is_complex(picture_is_complex);
-  layer->set_will_change(picture_will_change);
-  current_layer_->Add(std::move(layer));
-}
-
-#if defined(OS_FUCHSIA)
-void LayerBuilder::PushChildScene(
-    const SkPoint& offset,
-    const SkSize& size,
-    fxl::RefPtr<flow::ExportNodeHolder> export_token_holder,
-    bool hit_testable) {
-  if (!current_layer_) {
-    return;
-  }
-  SkRect sceneRect =
-      SkRect::MakeXYWH(offset.x(), offset.y(), size.width(), size.height());
-  if (!SkRect::Intersects(sceneRect, cull_rects_.top())) {
-    return;
-  }
-  auto layer = std::make_unique<flow::ChildSceneLayer>();
-  layer->set_offset(offset);
-  layer->set_size(size);
-  layer->set_export_node_holder(std::move(export_token_holder));
-  layer->set_hit_testable(hit_testable);
-  current_layer_->Add(std::move(layer));
-}
-#endif  // defined(OS_FUCHSIA)
-
-void LayerBuilder::Pop() {
-  if (!current_layer_) {
-    return;
-  }
-  cull_rects_.pop();
-  current_layer_ = current_layer_->parent();
-}
-
 int LayerBuilder::GetRasterizerTracingThreshold() const {
   return rasterizer_tracing_threshold_;
 }
@@ -205,29 +39,4 @@ void LayerBuilder::SetCheckerboardOffscreenLayers(bool checkerboard) {
   checkerboard_offscreen_layers_ = checkerboard;
 }
 
-std::unique_ptr<flow::Layer> LayerBuilder::TakeLayer() {
-  return std::move(root_layer_);
-}
-
-void LayerBuilder::PushLayer(std::unique_ptr<flow::ContainerLayer> layer,
-                             const SkRect& cullRect) {
-  FXL_DCHECK(layer);
-
-  cull_rects_.push(cullRect);
-
-  if (!root_layer_) {
-    root_layer_ = std::move(layer);
-    current_layer_ = root_layer_.get();
-    return;
-  }
-
-  if (!current_layer_) {
-    return;
-  }
-
-  flow::ContainerLayer* newLayer = layer.get();
-  current_layer_->Add(std::move(layer));
-  current_layer_ = newLayer;
-}
-
 }  // namespace flow

engine/src/flutter/flow/layers/layer_builder.h

@@ -6,9 +6,8 @@
 #define FLUTTER_FLOW_LAYERS_LAYER_BUILDER_H_
 
 #include <memory>
-#include <stack>
 
-#include "flutter/flow/layers/container_layer.h"
+#include "flutter/flow/layers/layer.h"
 #include "garnet/public/lib/fxl/macros.h"
 #include "third_party/skia/include/core/SkBlendMode.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ -24,48 +23,54 @@ namespace flow {
 
 class LayerBuilder {
  public:
+  static std::unique_ptr<LayerBuilder> Create();
+
   LayerBuilder();
 
-  ~LayerBuilder();
+  virtual ~LayerBuilder();
 
-  void PushTransform(const SkMatrix& matrix);
+  virtual void PushTransform(const SkMatrix& matrix) = 0;
 
-  void PushClipRect(const SkRect& rect);
+  virtual void PushClipRect(const SkRect& rect) = 0;
 
-  void PushClipRoundedRect(const SkRRect& rect);
+  virtual void PushClipRoundedRect(const SkRRect& rect) = 0;
 
-  void PushClipPath(const SkPath& path);
+  virtual void PushClipPath(const SkPath& path) = 0;
 
-  void PushOpacity(int alpha);
+  virtual void PushOpacity(int alpha) = 0;
 
-  void PushColorFilter(SkColor color, SkBlendMode blend_mode);
+  virtual void PushColorFilter(SkColor color, SkBlendMode blend_mode) = 0;
 
-  void PushBackdropFilter(sk_sp<SkImageFilter> filter);
+  virtual void PushBackdropFilter(sk_sp<SkImageFilter> filter) = 0;
 
-  void PushShaderMask(sk_sp<SkShader> shader,
-                      const SkRect& rect,
-                      SkBlendMode blend_mode);
+  virtual void PushShaderMask(sk_sp<SkShader> shader,
+                              const SkRect& rect,
+                              SkBlendMode blend_mode) = 0;
 
-  void PushPhysicalModel(const SkRRect& rect,
-                         double elevation,
-                         SkColor color,
-                         SkScalar device_pixel_ratio);
+  virtual void PushPhysicalModel(const SkRRect& rect,
+                                 double elevation,
+                                 SkColor color,
+                                 SkScalar device_pixel_ratio) = 0;
 
-  void PushPerformanceOverlay(uint64_t enabled_options, const SkRect& rect);
+  virtual void PushPerformanceOverlay(uint64_t enabled_options,
+                                      const SkRect& rect) = 0;
 
-  void PushPicture(const SkPoint& offset,
-                   sk_sp<SkPicture> picture,
-                   bool picture_is_complex,
-                   bool picture_will_change);
+  virtual void PushPicture(const SkPoint& offset,
+                           sk_sp<SkPicture> picture,
+                           bool picture_is_complex,
+                           bool picture_will_change) = 0;
 
 #if defined(OS_FUCHSIA)
-  void PushChildScene(const SkPoint& offset,
-                      const SkSize& size,
-                      fxl::RefPtr<flow::ExportNodeHolder> export_token_holder,
-                      bool hit_testable);
+  virtual void PushChildScene(
+      const SkPoint& offset,
+      const SkSize& size,
+      fxl::RefPtr<flow::ExportNodeHolder> export_token_holder,
+      bool hit_testable) = 0;
 #endif  // defined(OS_FUCHSIA)
 
-  void Pop();
+  virtual void Pop() = 0;
+
+  virtual std::unique_ptr<flow::Layer> TakeLayer() = 0;
 
   int GetRasterizerTracingThreshold() const;
 
@@ -79,18 +84,10 @@ class LayerBuilder {
 
   void SetCheckerboardOffscreenLayers(bool checkerboard);
 
-  std::unique_ptr<flow::Layer> TakeLayer();
-
  private:
-  std::unique_ptr<flow::ContainerLayer> root_layer_;
-  flow::ContainerLayer* current_layer_ = nullptr;
   int rasterizer_tracing_threshold_ = 0;
   bool checkerboard_raster_cache_images_ = false;
   bool checkerboard_offscreen_layers_ = false;
-  std::stack<SkRect> cull_rects_;
-
-  void PushLayer(std::unique_ptr<flow::ContainerLayer> layer,
-                 const SkRect& cullRect);
 
   FXL_DISALLOW_COPY_AND_ASSIGN(LayerBuilder);
 };

engine/src/flutter/lib/ui/compositing/scene_builder.cc

@@ -50,8 +50,7 @@ void SceneBuilder::RegisterNatives(tonic::DartLibraryNatives* natives) {
        FOR_EACH_BINDING(DART_REGISTER_NATIVE)});
 }
 
-SceneBuilder::SceneBuilder()
-    : layer_builder_(std::make_unique<flow::LayerBuilder>()){};
+SceneBuilder::SceneBuilder() : layer_builder_(flow::LayerBuilder::Create()) {}
 
 SceneBuilder::~SceneBuilder() = default;