Move ProxyServiceFactory to components/proxy_service/ios.

components/proxy_config/ios/BUILD.gn

Index: components/proxy_config/ios/BUILD.gn
diff --git a/components/proxy_config/ios/BUILD.gn b/components/proxy_config/ios/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..aafa2d3e81607338e280e42d05f71d087ea528ad
--- /dev/null
+++ b/components/proxy_config/ios/BUILD.gn
@@ -0,0 +1,19 @@
+# Copyright 2017 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.
+
+component("ios") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  deps = [
+    "//base",
+    "//components/proxy_config",
+    "//ios/web",
+    "//net",
+  ]
+
+  sources = [
+    "proxy_service_factory.cc",
+    "proxy_service_factory.h",
+  ]
+}