fuchsia: Remove dead code / break dependencies

The fuchsia code around metrics and sizing was just sending this
information through a side-channel, when the engine already had the
information available.  So, delete all of it to make future CLs simpler.

Additionally, the SceneUpdateContext has many unneccesary dependencies
re: metrics and PaintTasks.  Break those to make future CLs simpler.

Tested: Ran all unittests and ran workstation on Fuchsia
BUG: 53062, 53063

Author: arbreng

flow/compositor_context.cc

@@ -5,6 +5,7 @@
 #include "flutter/flow/compositor_context.h"
 
 #include "flutter/flow/layers/layer_tree.h"
+#include "flutter/fml/trace_event.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace flutter {

flow/gl_context_switch.cc

@@ -4,6 +4,8 @@
 
 #include "flutter/flow/gl_context_switch.h"
 
+#include "flutter/fml/logging.h"
+
 namespace flutter {
 
 SwitchableGLContext::SwitchableGLContext() = default;

flow/gl_context_switch.h

@@ -9,7 +9,6 @@
 #include <memory>
 #include <vector>
 
-#include "flutter/fml/logging.h"
 #include "flutter/fml/macros.h"
 
 namespace flutter {

flow/layers/backdrop_filter_layer.cc

@@ -4,6 +4,9 @@
 
 #include "flutter/flow/layers/backdrop_filter_layer.h"
 
+#include "flutter/fml/logging.h"
+#include "flutter/fml/trace_event.h"
+
 namespace flutter {
 
 BackdropFilterLayer::BackdropFilterLayer(sk_sp<SkImageFilter> filter)

flow/layers/backdrop_filter_layer.h

@@ -6,7 +6,7 @@
 #define FLUTTER_FLOW_LAYERS_BACKDROP_FILTER_LAYER_H_
 
 #include "flutter/flow/layers/container_layer.h"
-
+#include "flutter/fml/macros.h"
 #include "third_party/skia/include/core/SkImageFilter.h"
 
 namespace flutter {

flow/layers/backdrop_filter_layer_unittests.cc

@@ -23,7 +23,6 @@ TEST_F(BackdropFilterLayerTest, PaintingEmptyLayerDies) {
   layer->Preroll(preroll_context(), SkMatrix());
   EXPECT_EQ(layer->paint_bounds(), kEmptyRect);
   EXPECT_FALSE(layer->needs_painting());
-  EXPECT_FALSE(layer->needs_system_composite());
 
   EXPECT_DEATH_IF_SUPPORTED(layer->Paint(paint_context()),
                             "needs_painting\\(\\)");
@@ -206,7 +205,7 @@ TEST_F(BackdropFilterLayerTest, Readback) {
 
   // BDF with no filter blocks child with readback
   auto mock_layer =
-      std::make_shared<MockLayer>(SkPath(), SkPaint(), false, false, true);
+      std::make_shared<MockLayer>(SkPath(), SkPaint(), false, true);
   layer2->Add(mock_layer);
   preroll_context()->surface_needs_readback = false;
   layer2->Preroll(preroll_context(), initial_transform);

flow/layers/child_scene_layer.cc

@@ -5,6 +5,7 @@
 #include "flutter/flow/layers/child_scene_layer.h"
 
 #include "flutter/flow/view_holder.h"
+#include "flutter/fml/trace_event.h"
 
 namespace flutter {
 
@@ -19,16 +20,21 @@ ChildSceneLayer::ChildSceneLayer(zx_koid_t layer_id,
 
 void ChildSceneLayer::Preroll(PrerollContext* context, const SkMatrix& matrix) {
   TRACE_EVENT0("flutter", "ChildSceneLayer::Preroll");
-  set_needs_system_composite(true);
 
+  context->has_platform_view = true;
+  context->platform_view_exists_below = true;
   CheckForChildLayerBelow(context);
 
-  context->child_scene_layer_exists_below = true;
-
   // An alpha "hole punch" is required if the frame behind us is not opaque.
-  if (!context->is_opaque) {
-    set_paint_bounds(
-        SkRect::MakeXYWH(offset_.fX, offset_.fY, size_.fWidth, size_.fHeight));
+  for (auto i = context->mutators_stack.Bottom();
+       i != context->mutators_stack.Top(); ++i) {
+    const auto& mutator = *i;
+    if (mutator->GetType() == MutatorType::opacity &&
+        mutator->GetAlpha() < 255) {
+      set_paint_bounds(SkRect::MakeXYWH(offset_.fX, offset_.fY, size_.fWidth,
+                                        size_.fHeight));
+      break;
+    }
   }
 }
 

flow/layers/child_scene_layer.h

@@ -5,13 +5,12 @@
 #ifndef FLUTTER_FLOW_LAYERS_CHILD_SCENE_LAYER_H_
 #define FLUTTER_FLOW_LAYERS_CHILD_SCENE_LAYER_H_
 
+#include "flutter/flow/layers/layer.h"
+#include "flutter/flow/scene_update_context.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/core/SkPoint.h"
 #include "third_party/skia/include/core/SkSize.h"
 
-#include "flutter/flow/layers/layer.h"
-#include "flutter/flow/scene_update_context.h"
-
 namespace flutter {
 
 // Layer that represents an embedded child.

flow/layers/clip_path_layer.cc

@@ -4,9 +4,11 @@
 
 #include "flutter/flow/layers/clip_path_layer.h"
 
+#include "flutter/fml/trace_event.h"
+
 #if defined(LEGACY_FUCHSIA_EMBEDDER)
 
-#include "lib/ui/scenic/cpp/commands.h"
+#include "flutter/flow/scene_update_context.h"  //nogncheck
 
 #endif
 
@@ -48,7 +50,7 @@ void ClipPathLayer::UpdateScene(SceneUpdateContext& context) {
 
   // TODO(liyuqian): respect clip_behavior_
   SceneUpdateContext::Clip clip(context, clip_path_.getBounds());
-  UpdateSceneChildren(context);
+  ContainerLayer::UpdateScene(context);
 }
 
 #endif

flow/layers/clip_path_layer.h

@@ -7,6 +7,9 @@
 
 #include "flutter/flow/layers/container_layer.h"
 
+#include "flutter/fml/macros.h"
+#include "third_party/skia/include/core/SkPath.h"
+
 namespace flutter {
 
 class ClipPathLayer : public ContainerLayer {