Convert Web Store Inline Install IPCs to mojo

chrome/common/extensions/mojom/inline_install.mojom

+// Copyright 2017 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 extensions.mojom;
+
+[Native]
+enum WebstoreInstallResult;
+
+[Native]
+enum WebstoreInstallStage;
+
+interface InlineInstallProgressListener {
+  // Notifies the renderer when install stage updates were requested for an
+  // inline install.
+  InlineInstallStageChanged(WebstoreInstallStage stage);
+
+  // Notifies the renderer when download progress updates were requested for an
+  // inline install.
+  InlineInstallDownloadProgress(int32 percent_downloaded);
+};
+
+interface InlineInstaller {
+  // Sent by the renderer to implement chrome.webstore.install() and notifies
+  // the renderer once the installation is complete.
+  DoInlineInstall(
+      int32 install_id, string webstore_item_id, int32 listeners_mask,
+      InlineInstallProgressListener install_progress_listener) =>
+      (int32 install_id, bool success, string error,

[Devlin, 2017/05/24 21:33:59]

I think Ken's hope was to do-away with install_id completely at the mojo/browser
layers, which we should be able to do by binding it on the renderer side (since
the callback will only be associated with a single request).

[catmullings, 2017/05/25 00:14:44]

Done.

+      WebstoreInstallResult result);
+};
+
+