Revert of Host-side implementation of ARC Intent handler

components/arc/common/intent_helper.mojom

-// Copyright 2016 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.
-
-module arc;
-
-// Handles intents from ARC in Chrome.
-interface IntentHelperHost {
-  // Opens the url with Chrome for Chrome OS.
-  OnOpenUrl@0(string url);
-};
-
-// Sends intents to ARC on behalf of Chrome.
-interface IntentHelperInstance {
-  // Establishes full-duplex communication with the host.
-  Init@0(IntentHelperHost host_ptr);
-
-  // TODO(yusukes): Merge settings.mojom into intent_helper.mojom.
-};