[mac] Build mac framework with app extension flag

ci/licenses_golden/licenses_flutter

@@ -2677,6 +2677,7 @@ ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTex
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTextInputSemanticsObjectTest.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTextureRegistrar.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTextureRegistrar.mm + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterUmbrellaImportTests.m + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterView.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterView.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController.mm + ../../../flutter/LICENSE
@@ -5276,6 +5277,7 @@ FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTextu
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterTextureRegistrar.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterThreadSynchronizer.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterThreadSynchronizer.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterUmbrellaImportTests.m
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterView.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterView.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController.mm

common/config.gni

@@ -61,6 +61,10 @@ if (is_ios || is_mac) {
     "-Werror=overriding-method-mismatch",
     "-Werror=undeclared-selector",
   ]
+  if (is_mac) {
+    flutter_cflags_objc += [ "-fapplication-extension" ]
+  }
+
   flutter_cflags_objcc = flutter_cflags_objc
   flutter_cflags_objc_arc = flutter_cflags_objc + [ "-fobjc-arc" ]
   flutter_cflags_objcc_arc = flutter_cflags_objc_arc

shell/platform/darwin/macos/BUILD.gn

@@ -149,7 +149,10 @@ shared_library("flutter_framework_dylib") {
   visibility = [ ":*" ]
   output_name = "$_flutter_framework_name"
 
-  ldflags = [ "-Wl,-install_name,@rpath/$_flutter_framework_filename/$_framework_binary_subpath" ]
+  ldflags = [
+    "-Wl,-install_name,@rpath/$_flutter_framework_filename/$_framework_binary_subpath",
+    "-fapplication-extension",
+  ]
 
   deps = [ ":flutter_framework_source" ]
 }
@@ -297,7 +300,7 @@ action("_generate_symlinks") {
 }
 
 group("flutter_framework") {
-  deps = [ ":_generate_symlinks" ]
+  deps = [ ":_generate_symlinks_and_verify_framework_module" ]
 }
 
 if (build_glfw_shell) {
@@ -334,3 +337,21 @@ generated_file("macos_framework_without_entitlement_config") {
 
   deps = [ ":_generate_symlinks" ]
 }
+
+shared_library("_generate_symlinks_and_verify_framework_module") {
+  framework_search_path = rebase_path("$root_out_dir")
+  visibility = [ ":*" ]
+  cflags_objc = [ "-F$framework_search_path" ]
+
+  ldflags = [
+    "-F$framework_search_path",
+    "-fapplication-extension",
+    "-Xlinker",
+    "-fatal_warnings",
+  ]
+  frameworks = [ "FlutterMacOS.framework" ]
+
+  sources = [ "framework/Source/FlutterUmbrellaImportTests.m" ]
+
+  deps = [ ":_generate_symlinks" ]
+}

shell/platform/darwin/macos/framework/Source/FlutterUmbrellaImportTests.m

@@ -0,0 +1,11 @@
+// Copyright 2013 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.
+
+// FLUTTER_NOLINT: https://github.com/flutter/flutter/issues/93360
+
+// The only point of this file is to ensure that the Flutter framework umbrella header can be
+// cleanly imported from an Objective-C translation unit. The target that uses this file copies the
+// headers to a path that simulates how users would actually import the framework outside of the
+// engine source root.
+#import <FlutterMacOS/FlutterMacOS.h>