fuchsia: Add scaffolding and basic implementation for flatland migration

ci/licenses_golden/licenses_flutter

@@ -1386,6 +1386,12 @@ FILE: ../../../flutter/shell/platform/fuchsia/flutter/component.h
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/component_unittest.cc
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/engine.cc
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/engine.h
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/flatland_connection.cc
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/flatland_connection.h
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/flatland_external_view_embedder.cc
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/flatland_external_view_embedder.h
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/flatland_platform_view.cc
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/flatland_platform_view.h
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/flutter_runner_fakes.h
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/flutter_runner_product_configuration.cc
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/flutter_runner_product_configuration.h
@@ -1397,6 +1403,8 @@ FILE: ../../../flutter/shell/platform/fuchsia/flutter/fuchsia_external_view_embe
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/fuchsia_intl.cc
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/fuchsia_intl.h
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/fuchsia_intl_unittest.cc
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/gfx_platform_view.cc
+FILE: ../../../flutter/shell/platform/fuchsia/flutter/gfx_platform_view.h
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/gfx_session_connection.cc
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/gfx_session_connection.h
 FILE: ../../../flutter/shell/platform/fuchsia/flutter/isolate_configurator.cc

shell/platform/fuchsia/flutter/BUILD.gn

@@ -59,6 +59,12 @@ template("runner_sources") {
       "component.h",
       "engine.cc",
       "engine.h",
+      "flatland_connection.cc",
+      "flatland_connection.h",
+      "flatland_external_view_embedder.cc",
+      "flatland_external_view_embedder.h",
+      "flatland_platform_view.cc",
+      "flatland_platform_view.h",
       "flutter_runner_product_configuration.cc",
       "flutter_runner_product_configuration.h",
       "focus_delegate.cc",
@@ -67,6 +73,8 @@ template("runner_sources") {
       "fuchsia_external_view_embedder.h",
       "fuchsia_intl.cc",
       "fuchsia_intl.h",
+      "gfx_platform_view.cc",
+      "gfx_platform_view.h",
       "gfx_session_connection.cc",
       "gfx_session_connection.h",
       "isolate_configurator.cc",
@@ -129,6 +137,7 @@ template("runner_sources") {
              "$fuchsia_sdk_root/fidl:fuchsia.io",
              "$fuchsia_sdk_root/fidl:fuchsia.sys",
              "$fuchsia_sdk_root/fidl:fuchsia.ui.app",
+             "$fuchsia_sdk_root/fidl:fuchsia.ui.composition",
              "$fuchsia_sdk_root/fidl:fuchsia.ui.scenic",
              "$fuchsia_sdk_root/pkg:async-cpp",
              "$fuchsia_sdk_root/pkg:async-default",

shell/platform/fuchsia/flutter/component.cc

@@ -639,6 +639,29 @@ void Application::CreateViewWithViewRef(
       ));
 }
 
+void Application::CreateView2(fuchsia::ui::app::CreateView2Args view_args) {
+  if (!svc_) {
+    FML_DLOG(ERROR)
+        << "Component incoming services was invalid when attempting to "
+           "create a shell for a view provider request.";
+    return;
+  }
+
+  shell_holders_.emplace(std::make_unique<Engine>(
+      *this,                      // delegate
+      debug_label_,               // thread label
+      svc_,                       // Component incoming services
+      runner_incoming_services_,  // Runner incoming services
+      settings_,                  // settings
+      std::move(
+          *view_args.mutable_view_creation_token()),  // view creation token
+      scenic::ViewRefPair::New(),                     // view ref pair
+      std::move(fdio_ns_),                            // FDIO namespace
+      std::move(directory_request_),                  // outgoing request
+      product_config_                                 // product configuration
+      ));
+}
+
 #if !defined(DART_PRODUCT)
 void Application::WriteProfileToTrace() const {
   for (const auto& engine : shell_holders_) {

shell/platform/fuchsia/flutter/component.h

@@ -128,6 +128,9 @@ class Application final : public Engine::Delegate,
                              fuchsia::ui::views::ViewRefControl control_ref,
                              fuchsia::ui::views::ViewRef view_ref) override;
 
+  // |fuchsia::ui::app::ViewProvider|
+  void CreateView2(fuchsia::ui::app::CreateView2Args view_args) override;
+
   // |flutter::Engine::Delegate|
   void OnEngineTerminate(const Engine* holder) override;