Revert "IOS Platform view transform/clipping (flutter#9075)"

This reverts commit ebb5b90.

Seeing the following breakage on host build:
```
../../flutter/flow/scene_update_context.cc:205:36: error: non-const lvalue reference to type 'flutter::MutatorsStack' cannot bind to a value of unrelated type 'const flutter::Stopwatch'
                                   frame.context().raster_time(),
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../flutter/flow/scene_update_context.cc:207:36: error: no viable conversion from 'flutter::TextureRegistry' to 'const flutter::Stopwatch'
                                   frame.context().texture_registry(),
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../flutter/flow/instrumentation.h:55:32: note: candidate constructor not viable: no known conversion from 'flutter::TextureRegistry' to 'const flutter::Stopwatch &' for 1st argument
  FML_DISALLOW_COPY_AND_ASSIGN(Stopwatch);
                               ^
../../flutter/fml/macros.h:28:3: note: expanded from macro 'FML_DISALLOW_COPY_AND_ASSIGN'
  TypeName(const TypeName&) = delete;          \
  ^
../../flutter/flow/scene_update_context.cc:208:36: error: non-const lvalue reference to type 'flutter::TextureRegistry' cannot bind to a temporary of type 'flutter::RasterCache *'
                                   &frame.context().raster_cache(),
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../flutter/flow/scene_update_context.cc:209:36: error: cannot initialize a member subobject of type 'const flutter::RasterCache *' with an rvalue of type 'bool'
                                   false};
                                   ^~~~~
```

ci/licenses_golden/licenses_flutter

@@ -71,7 +71,6 @@ FILE: ../../../flutter/flow/layers/transform_layer.h
 FILE: ../../../flutter/flow/matrix_decomposition.cc
 FILE: ../../../flutter/flow/matrix_decomposition.h
 FILE: ../../../flutter/flow/matrix_decomposition_unittests.cc
-FILE: ../../../flutter/flow/mutators_stack_unittests.cc
 FILE: ../../../flutter/flow/paint_utils.cc
 FILE: ../../../flutter/flow/paint_utils.h
 FILE: ../../../flutter/flow/raster_cache.cc

flow/BUILD.gn

@@ -114,7 +114,6 @@ executable("flow_unittests") {
     "layers/performance_overlay_layer_unittests.cc",
     "layers/physical_shape_layer_unittests.cc",
     "matrix_decomposition_unittests.cc",
-    "mutators_stack_unittests.cc",
     "raster_cache_unittests.cc",
   ]
 

flow/embedded_views.cc

@@ -9,34 +9,4 @@ namespace flutter {
 bool ExternalViewEmbedder::SubmitFrame(GrContext* context) {
   return false;
 };
-
-void MutatorsStack::pushClipRect(const SkRect& rect) {
-  std::shared_ptr<Mutator> element = std::make_shared<Mutator>(rect);
-  vector_.push_back(element);
-};
-
-void MutatorsStack::pushClipRRect(const SkRRect& rrect) {
-  std::shared_ptr<Mutator> element = std::make_shared<Mutator>(rrect);
-  vector_.push_back(element);
-};
-
-void MutatorsStack::pushTransform(const SkMatrix& matrix) {
-  std::shared_ptr<Mutator> element = std::make_shared<Mutator>(matrix);
-  vector_.push_back(element);
-};
-
-void MutatorsStack::pop() {
-  vector_.pop_back();
-};
-
-const std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator
-MutatorsStack::top() const {
-  return vector_.rend();
-};
-
-const std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator
-MutatorsStack::bottom() const {
-  return vector_.rbegin();
-};
-
 }  // namespace flutter

flow/embedded_views.h

@@ -9,178 +9,25 @@
 
 #include "flutter/fml/memory/ref_counted.h"
 #include "third_party/skia/include/core/SkCanvas.h"
-#include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/core/SkPoint.h"
-#include "third_party/skia/include/core/SkRRect.h"
-#include "third_party/skia/include/core/SkRect.h"
 #include "third_party/skia/include/core/SkSize.h"
 
 namespace flutter {
 
-enum MutatorType { clip_rect, clip_rrect, clip_path, transform };
-
-// Stores mutation information like clipping or transform.
-//
-// The `type` indicates the type of the mutation: clip_rect, transform and etc.
-// Each `type` is paired with an object that supports the mutation. For example,
-// if the `type` is clip_rect, `rect()` is used the represent the rect to be
-// clipped. One mutation object must only contain one type of mutation.
-class Mutator {
- public:
-  Mutator(const Mutator& other) {
-    type_ = other.type_;
-    switch (other.type_) {
-      case clip_rect:
-        rect_ = other.rect_;
-        break;
-      case clip_rrect:
-        rrect_ = other.rrect_;
-        break;
-      case clip_path:
-        path_ = new SkPath(*other.path_);
-        break;
-      case transform:
-        matrix_ = other.matrix_;
-        break;
-      default:
-        break;
-    }
-  }
-
-  explicit Mutator(const SkRect& rect) : type_(clip_rect), rect_(rect) {}
-  explicit Mutator(const SkRRect& rrect) : type_(clip_rrect), rrect_(rrect) {}
-  explicit Mutator(const SkPath& path)
-      : type_(clip_path), path_(new SkPath(path)) {}
-  explicit Mutator(const SkMatrix& matrix)
-      : type_(transform), matrix_(matrix) {}
-
-  const MutatorType& type() const { return type_; }
-  const SkRect& rect() const { return rect_; }
-  const SkRRect& rrect() const { return rrect_; }
-  const SkPath& path() const { return *path_; }
-  const SkMatrix& matrix() const { return matrix_; }
-
-  bool operator==(const Mutator& other) const {
-    if (type_ != other.type_) {
-      return false;
-    }
-    if (type_ == clip_rect && rect_ == other.rect_) {
-      return true;
-    }
-    if (type_ == clip_rrect && rrect_ == other.rrect_) {
-      return true;
-    }
-    if (type_ == clip_path && *path_ == *other.path_) {
-      return true;
-    }
-    if (type_ == transform && matrix_ == other.matrix_) {
-      return true;
-    }
-
-    return false;
-  }
-
-  bool operator!=(const Mutator& other) const { return !operator==(other); }
-
-  bool isClipType() {
-    return type_ == clip_rect || type_ == clip_rrect || type_ == clip_path;
-  }
-
-  ~Mutator() {
-    if (type_ == clip_path) {
-      delete path_;
-    }
-  };
-
- private:
-  MutatorType type_;
-
-  union {
-    SkRect rect_;
-    SkRRect rrect_;
-    SkMatrix matrix_;
-    SkPath* path_;
-  };
-
-};  // Mutator
-
-// A stack of mutators that can be applied to an embedded platform view.
-//
-// The stack may include mutators like transforms and clips, each mutator
-// applies to all the mutators that are below it in the stack and to the
-// embedded view.
-//
-// For example consider the following stack: [T1, T2, T3], where T1 is the top
-// of the stack and T3 is the bottom of the stack. Applying this mutators stack
-// to a platform view P1 will result in T1(T2(T2(P1))).
-class MutatorsStack {
- public:
-  MutatorsStack() = default;
-
-  void pushClipRect(const SkRect& rect);
-  void pushClipRRect(const SkRRect& rrect);
-  void pushClipPath(const SkPath& path);
-
-  void pushTransform(const SkMatrix& matrix);
-
-  // Removes the `Mutator` on the top of the stack
-  // and destroys it.
-  void pop();
-
-  // Returns an iterator pointing to the top of the stack.
-  const std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator top()
-      const;
-  // Returns an iterator pointing to the bottom of the stack.
-  const std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator bottom()
-      const;
-
-  bool operator==(const MutatorsStack& other) const {
-    if (vector_.size() != other.vector_.size()) {
-      return false;
-    }
-    for (size_t i = 0; i < vector_.size(); i++) {
-      if (*vector_[i] != *other.vector_[i]) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  bool operator!=(const MutatorsStack& other) const {
-    return !operator==(other);
-  }
-
- private:
-  std::vector<std::shared_ptr<Mutator>> vector_;
-};  // MutatorsStack
-
 class EmbeddedViewParams {
  public:
-  EmbeddedViewParams() = default;
-
-  EmbeddedViewParams(const EmbeddedViewParams& other) {
-    offsetPixels = other.offsetPixels;
-    sizePoints = other.sizePoints;
-    mutatorsStack = other.mutatorsStack;
-  };
-
   SkPoint offsetPixels;
   SkSize sizePoints;
-  MutatorsStack mutatorsStack;
 
   bool operator==(const EmbeddedViewParams& other) const {
-    return offsetPixels == other.offsetPixels &&
-           sizePoints == other.sizePoints &&
-           mutatorsStack == other.mutatorsStack;
+    return offsetPixels == other.offsetPixels && sizePoints == other.sizePoints;
   }
 };
 
 // This is only used on iOS when running in a non headless mode,
 // in this case ExternalViewEmbedder is a reference to the
 // FlutterPlatformViewsController which is owned by FlutterViewController.
 class ExternalViewEmbedder {
-  // TODO(cyanglaz): Make embedder own the `EmbeddedViewParams`.
-
  public:
   ExternalViewEmbedder() = default;
 
@@ -199,8 +46,7 @@ class ExternalViewEmbedder {
   virtual ~ExternalViewEmbedder() = default;
 
   FML_DISALLOW_COPY_AND_ASSIGN(ExternalViewEmbedder);
-
-};  // ExternalViewEmbedder
+};
 
 }  // namespace flutter
 

flow/layers/clip_rect_layer.cc

@@ -50,16 +50,13 @@ void ClipRectLayer::Paint(PaintContext& context) const {
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->clipRect(clip_rect_,
                                           clip_behavior_ != Clip::hardEdge);
-  context.mutators_stack.pushClipRect(clip_rect_);
-
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->saveLayer(clip_rect_, nullptr);
   }
   PaintChildren(context);
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->restore();
   }
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter

flow/layers/clip_rrect_layer.cc

@@ -58,16 +58,13 @@ void ClipRRectLayer::Paint(PaintContext& context) const {
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->clipRRect(clip_rrect_,
                                            clip_behavior_ != Clip::hardEdge);
-  context.mutators_stack.pushClipRRect(clip_rrect_);
-
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->saveLayer(paint_bounds(), nullptr);
   }
   PaintChildren(context);
   if (clip_behavior_ == Clip::antiAliasWithSaveLayer) {
     context.internal_nodes_canvas->restore();
   }
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter

flow/layers/layer.h

@@ -83,7 +83,6 @@ class Layer {
     SkCanvas* leaf_nodes_canvas;
     GrContext* gr_context;
     ExternalViewEmbedder* view_embedder;
-    MutatorsStack& mutators_stack;
     const Stopwatch& raster_time;
     const Stopwatch& ui_time;
     TextureRegistry& texture_registry;

flow/layers/layer_tree.cc

@@ -83,13 +83,11 @@ void LayerTree::Paint(CompositorContext::ScopedFrame& frame,
     }
   }
 
-  MutatorsStack stack;
   Layer::PaintContext context = {
       (SkCanvas*)&internal_nodes_canvas,
       frame.canvas(),
       frame.gr_context(),
       frame.view_embedder(),
-      stack,
       frame.context().raster_time(),
       frame.context().ui_time(),
       frame.context().texture_registry(),
@@ -110,7 +108,6 @@ sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
     return nullptr;
   }
 
-  MutatorsStack unused_stack;
   const Stopwatch unused_stopwatch;
   TextureRegistry unused_texture_registry;
   SkMatrix root_surface_transformation;
@@ -138,7 +135,6 @@ sk_sp<SkPicture> LayerTree::Flatten(const SkRect& bounds) {
       canvas,  // canvas
       nullptr,
       nullptr,
-      unused_stack,
       unused_stopwatch,         // frame time (dont care)
       unused_stopwatch,         // engine time (dont care)
       unused_texture_registry,  // texture registry (not supported)

flow/layers/performance_overlay_layer_unittests.cc

@@ -47,13 +47,10 @@ TEST(PerformanceOverlayLayer, Gold) {
   ASSERT_TRUE(surface != nullptr);
 
   flutter::TextureRegistry unused_texture_registry;
-  flutter::MutatorsStack unused_stack;
+
   flutter::Layer::PaintContext paintContext = {
-      nullptr,        surface->getCanvas(),
-      nullptr,        nullptr,
-      unused_stack,   mock_stopwatch,
-      mock_stopwatch, unused_texture_registry,
-      nullptr,        false};
+      nullptr,        surface->getCanvas(),    nullptr, nullptr, mock_stopwatch,
+      mock_stopwatch, unused_texture_registry, nullptr, false};
 
   // Specify font file to ensure the same font across different operation
   // systems.

flow/layers/platform_view_layer.cc

@@ -37,7 +37,6 @@ void PlatformViewLayer::Paint(PaintContext& context) const {
   params.offsetPixels =
       SkPoint::Make(transform.getTranslateX(), transform.getTranslateY());
   params.sizePoints = size_;
-  params.mutatorsStack = context.mutators_stack;
 
   SkCanvas* canvas =
       context.view_embedder->CompositeEmbeddedView(view_id_, params);

flow/layers/transform_layer.cc

@@ -66,10 +66,7 @@ void TransformLayer::Paint(PaintContext& context) const {
 
   SkAutoCanvasRestore save(context.internal_nodes_canvas, true);
   context.internal_nodes_canvas->concat(transform_);
-  context.mutators_stack.pushTransform(transform_);
-
   PaintChildren(context);
-  context.mutators_stack.pop();
 }
 
 }  // namespace flutter