Add calls to the server to request WebAPK updates.

chrome/browser/android/webapk/webapk.proto

 // 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.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package webapk;
 
-// Response to "create" request.
+// Response after creating or updating a WebAPK.
 message WebApkResponse {
   // Package name to install WebAPK at.
   optional string package_name = 1;
 
+  // Version code of the WebAPK.
+  optional string version = 2;
+
   // URL to download WebAPK.
   optional string signed_download_url = 3;
 
-  reserved 2, 4;
+  reserved 4;
 }
 
-// Sent as part of request to create a WebAPK.
+// Sent as part of request to create or update a WebAPK.
 message WebApk {
+  // Package name of the WebAPK.
+  optional string package_name = 1;
+
+  // Version code of the WebAPK.
+  optional string version = 2;
+
   // The URL of the Web App Manifest.
   optional string manifest_url = 3;
 
   // Chrome's package name.
   optional string requester_application_package = 5;
 
   // Chrome's version.
   optional string requester_application_version = 6;
 
   // The Web App Manifest.
   optional WebAppManifest manifest = 7;
 
-  reserved 1, 2, 4;
+  reserved 4;
 }
 
 // Contains data from the Web App Manifest.
 message WebAppManifest {
   optional string name = 1;
   optional string short_name = 2;
   optional string start_url = 4;
   repeated string scopes = 5;
   repeated Image icons = 6;
   optional string orientation = 9;
@@ skipping 11 matching lines @@
   // Murmur2 hash of the icon's bytes. There should not be any transformations
   // applied to the icon's bytes prior to taking the Murmur2 hash.
   optional string hash = 5;
 
   // Actual bytes of the image. This image may be re-encoded from the original
   // image and may not match the murmur2 hash field above.
   optional bytes image_data = 6;
 
   reserved 2 to 4;
 }