This CL adds support for extension in GYP.

test/ios/extension/ExtensionContainer/AppDelegate.h

Index: test/ios/extension/ExtensionContainer/AppDelegate.h
diff --git a/test/win/ml-safeseh/hello.cc b/test/ios/extension/ExtensionContainer/AppDelegate.h
similarity index 53%
copy from test/win/ml-safeseh/hello.cc
copy to test/ios/extension/ExtensionContainer/AppDelegate.h
index 6141300d2c0a517a8f79075619d089be0ddbf2ea..510e2300b1c6e69ae4d868f4136dc5958d6dfabd 100644
--- a/test/win/ml-safeseh/hello.cc
+++ b/test/ios/extension/ExtensionContainer/AppDelegate.h
@@ -2,10 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-extern "C" {
-int zero(void);
-}
+#import <UIKit/UIKit.h>
+
+@interface AppDelegate : UIResponder <UIApplicationDelegate>
+
+@property (strong, nonatomic) UIWindow *window;
+
+@end
 
-int main() {
-  return zero();
-}