Add gn implementation for //components/dom_distiller/ios.

components/dom_distiller/ios/BUILD.gn

Index: components/dom_distiller/ios/BUILD.gn
diff --git a/components/dom_distiller/ios/BUILD.gn b/components/dom_distiller/ios/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..35a4a1843d08923b40f773480aaa321564daf598
--- /dev/null
+++ b/components/dom_distiller/ios/BUILD.gn
@@ -0,0 +1,18 @@
+# Copyright 2015 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.
+
+source_set("ios") {
+  sources = [
+    "distiller_page_factory_ios.h",
+    "distiller_page_factory_ios.mm",
+    "distiller_page_ios.h",
+    "distiller_page_ios.mm",
+  ]
+
+  deps = [
+    "//components/dom_distiller/core",
+    "//components/dom_distiller/core/proto",
+    "//ios/public/provider/web",
+  ]
+}