This CL adds support for extension in GYP.

test/ios/extension/ExtensionContainer/ViewController.m

+//
+//  ViewController.m
+//  ExtensionContainer
+//
+//  Created by Olivier Robin on 6/27/14.
+//  Copyright (c) 2014 Olivier Robin. All rights reserved.
+//
+
+#import "ViewController.h"
+
+@interface ViewController ()
+
+
+@end
+
+@implementation ViewController
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+  // Do any additional setup after loading the view, typically from a nib.
+}
+
+- (void)didReceiveMemoryWarning {
+  [super didReceiveMemoryWarning];
+  // Dispose of any resources that can be recreated.
+}
+
+@end