Convert app banners to use Mojo.

third_party/WebKit/public/platform/modules/app_banner/app_banner.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 blink.mojom;
+
+enum AppBannerPromptReply {
+    NONE,
+    CANCEL,
+};
+
+interface AppBannerClient {
+    // Called from the browser to ask the renderer if the app banner should be
+    // shown.
+    BannerPromptRequest(int32 request_id, string platform) =>

[Sam McNally, 2016/10/06 07:17:44]

Two space indent.

[dominickn, 2016/10/06 22:58:12]

Done.

+        (int32 request_id, AppBannerPromptReply reply, string? referrer);
+};
+
+interface AppBannerEvent {
+    // Called from the browser to inform the event that the app banner was
+    // accepted or dismissed.
+    BannerAccepted(int32 request_id, string platform);
+    BannerDismissed(int32 request_id);
+};
+
+interface AppBannerService {
+    // Called to the browser from the renderer to display a previously offered
+    // app banner.
+    DisplayAppBanner(int32 request_id);
+
+    SetEvent(AppBannerEvent event);
+};