Create an Xcode project template for dynamic service creation. (flutter/engine#2695)

* Create an Xcode project template for dynamic service creation.

The `create_native_service_sdk.py` will be run on the buildbot similar
to `create_ios_sdk.py`. This will create an Xcode project with both arm
and x64 assets that the user can use to fill in the service
implementation.

* Add the complete_static_lib property to sdk_lib_archive in
dynamic/BUILD.gn

engine/src/flutter/BUILD.gn

@@ -11,7 +11,7 @@ group("default") {
 
   if (is_ios) {
     deps += [
-      "//sky/services/dynamic:sdk_lib",
+      "//sky/services/dynamic:sdk_lib_archive",
       "//sky/shell:flutter_framework",
     ]
   }

engine/src/flutter/sky/tools/create_ios_native_service_sdk.py

@@ -0,0 +1,99 @@
+#!/usr/bin/env python
+# Copyright 2016 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.
+
+'''Creates the iOS native service SDK that developers can use the create
+native services that can be dynamically loaded.'''
+
+import errno
+import os
+import shutil
+import sys
+import argparse
+import subprocess
+
+
+def mkdir_p(path):
+  try:
+    os.makedirs(path)
+  except OSError as exc:
+    if exc.errno == errno.EEXIST and os.path.isdir(path):
+      pass
+    else:
+      raise
+
+
+def main():
+  parser = argparse.ArgumentParser(description=__doc__)
+
+  parser.add_argument('--simulator-out-dir',
+                      dest='simulator_out_dir',
+                      required=True,
+                      help='The out directory for the simulator assets.')
+  parser.add_argument('--device-out-dir',
+                      dest='device_out_dir',
+                      required=True,
+                      help='The out directory for the device assets.')
+  parser.add_argument('--dest',
+                      dest='dest',
+                      required=True,
+                      help='The directory in which to create the SDK.')
+  parser.add_argument('--harness',
+                      dest='harness',
+                      required=True,
+                      help='The SDK harness to use.')
+  parser.add_argument('headers',
+                  metavar='H',
+                  nargs='+',
+                  help='A list of header directories to copy over to the SDK.')
+
+  args = parser.parse_args()
+
+  simulator_out_dir = os.path.abspath(args.simulator_out_dir)
+  device_out_dir = os.path.abspath(args.device_out_dir)
+
+  archive_path = 'obj/sky/services/dynamic/libFlutterService.a'
+
+  simulator_archive = os.path.join(simulator_out_dir, archive_path)
+  device_archive = os.path.join(device_out_dir, archive_path)
+
+  sdk_dir = os.path.join(os.path.abspath(args.dest), 'ServiceSDK')
+
+  if os.path.isdir(sdk_dir):
+    shutil.rmtree(sdk_dir)
+
+  shutil.copytree(os.path.abspath(args.harness), os.path.join(sdk_dir))
+
+  library_path = os.path.join(sdk_dir, 'Library')
+  header_path = os.path.join(sdk_dir, 'Headers')
+
+  mkdir_p(library_path)
+  mkdir_p(header_path)
+
+  subprocess.call([
+    'lipo',
+    simulator_archive,
+    device_archive,
+    '-create',
+    '-output',
+    os.path.join(library_path, 'libFlutterService.a'),
+  ])
+
+  src_root = os.path.join(os.path.dirname(__file__), '../../')
+  for headers_dir in args.headers:
+    for root, _, files in os.walk(headers_dir):
+      for file in files:
+        if file.endswith(".h"):
+          source = os.path.abspath(os.path.join(root, file))
+          relative = os.path.relpath(source, src_root)
+          destination = os.path.abspath(os.path.join(header_path, relative))
+          destination_dir = os.path.dirname(destination)
+          mkdir_p(destination_dir)
+          shutil.copyfile(source, destination)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())