[ios Mojo] iOS facade class for Mojo API.

ios/web/BUILD.gn

Index: ios/web/BUILD.gn
diff --git a/ios/web/BUILD.gn b/ios/web/BUILD.gn
index 0c3444eb57513fe426bb46b46a7151d42a5a1c22..f1d597948d8f6d8ff1650e49c29164456816cb6a 100644
--- a/ios/web/BUILD.gn
+++ b/ios/web/BUILD.gn
@@ -232,6 +232,8 @@ source_set("web") {
     "webui/crw_web_ui_manager.mm",
     "webui/crw_web_ui_page_builder.h",
     "webui/crw_web_ui_page_builder.mm",
+    "webui/mojo_facade.h",
+    "webui/mojo_facade.mm",
     "webui/shared_resources_data_source_ios.h",
     "webui/shared_resources_data_source_ios.mm",
     "webui/url_data_manager_ios.cc",
@@ -286,6 +288,7 @@ source_set("test_support") {
     "//base/test:test_support",
     "//ios/testing:ocmock_support",
     "//ios/third_party/gcdwebserver",
+    "//ios/web/test:mojo_bindings",

[Eugene But (OOO till 7-30), 2016/05/12 20:48:10]

This gives me gn error: 
https://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator-gn...

     "//net:test_support",
     "//testing/gmock",
     "//testing/gtest",
@@ -428,6 +431,7 @@ test("ios_web_unittests") {
     "web_state/wk_web_view_security_util_unittest.mm",
     "webui/crw_web_ui_manager_unittest.mm",
     "webui/crw_web_ui_page_builder_unittest.mm",
+    "webui/mojo_facade_unittest.mm",
     "webui/url_fetcher_block_adapter_unittest.mm",
   ]
 }