Convert ios_web_shell_test to GN.

build/config/ios/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ios/ios_sdk.gni")
 import("//build/config/sysroot.gni")
 import("//build/toolchain/toolchain.gni")
 
 # This is included by reference in the //build/config/compiler:runtime_library
 # config that is applied to all targets. It is here to separate out the logic
@@ skipping 23 matching lines @@
       "-isystem",
       rebase_path("//third_party/llvm-build/Release+Asserts/include/c++/v1",
                   root_build_dir),
     ]
   }
 }
 
 config("ios_dynamic_flags") {
   ldflags = [ "-Wl,-ObjC" ]  # Always load Objective-C categories and class.
 }
+
+config("xctest_config") {
+  common_flags = [
+    "-F",
+    "$ios_sdk_platform_path/Developer/Library/Frameworks",
+  ]
+
+  cflags = common_flags
+  ldflags = common_flags
+
+  libs = [
+    "Foundation.framework",
+    "XCTest.framework",
+  ]
+}