[iOS] Define global assert_no_deps and use it to prevent regressions.

ui/events/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("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/ozone/ozone.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
+if (is_ios) {
+  import("//ios/build/config.gni")
+}
+
 static_library("dom_keycode_converter") {
   sources = [
     "keycodes/dom/dom_code.h",
     "keycodes/dom/dom_key.h",
     "keycodes/dom/dom_key_data.inc",
     "keycodes/dom/keycode_converter.cc",
     "keycodes/dom/keycode_converter.h",
     "keycodes/dom/keycode_converter_data.inc",
   ]
 
@@ skipping 429 matching lines @@
   if (use_aura) {
     sources += [
       "gestures/gesture_provider_aura_unittest.cc",
       "gestures/motion_event_aura_unittest.cc",
     ]
   }
 
   if (is_android) {
     sources += [ "android/motion_event_android_unittest.cc" ]
   }
+
+  if (is_ios) {
+    assert_no_deps = ios_assert_no_deps
+  }
 }
 
 if (is_android) {
   generate_jar_jni("motionevent_jni_headers") {
     jni_package = "ui"
     classes = [ "android/view/MotionEvent.class" ]
   }
 
   generate_jar_jni("keyevent_jni_headers") {
     jni_package = "ui"
     classes = [ "android/view/KeyEvent.class" ]
   }
 }