Add visibility restrictions to all mojoms that export symbols.

mojo/public/interfaces/bindings/tests/BUILD.gn

 # Copyright 2014 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.
 
 import("../../../tools/bindings/mojom.gni")
 
 mojom("test_interfaces") {
   testonly = true
   sources = [
     "math_calculator.mojom",
@@ skipping 43 matching lines @@
   ]
   export_class_attribute = "MOJO_TEST_EXPORT"
   export_define = "MOJO_TEST_IMPLEMENTATION=1"
   export_header = "mojo/public/cpp/bindings/tests/mojo_test_export.h"
   if (!is_ios) {
     export_class_attribute_blink = "MOJO_TEST_BLINK_EXPORT"
     export_define_blink = "MOJO_TEST_BLINK_IMPLEMENTATION=1"
     export_header_blink =
         "mojo/public/cpp/bindings/tests/mojo_test_blink_export.h"
   }
-  visibility = [
-    ":test_export_component",
-    ":test_export_blink_component",
-  ]
+  visibility = [ ":test_export_component" ]
+  if (!is_ios) {
+    visibility_blink = [ ":test_export_blink_component" ]
+  }
 }
 
 mojom("test_exported_import") {
   testonly = true
   sources = [
     "test_import.mojom",
   ]
   public_deps = [
     ":test_export",
   ]
@@ skipping 88 matching lines @@
   ]
 }
 
 mojom("test_no_sources") {
   testonly = true
 
   public_deps = [
     ":test_interfaces",
   ]
 }