Add "usages" field to Image in WebApk.proto

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;
 
@@ skipping 53 matching lines @@
   repeated Image icons = 6;
   optional string orientation = 9;
   optional string display_mode = 10;
   optional string theme_color = 11;
   optional string background_color = 12;
 
   reserved 3, 7, 8, 13, 14;
 }
 
 message Image {
+
+  enum Usage {
+    PRIMARY_ICON = 1;
+    BADGE_ICON = 2;
+  }
+
   // Image's URL.
   optional string src = 1;
 
   // 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;
+  // Specifies Chrome's intended usages for the image.
+  repeated Usage usages = 8;
+
+  reserved 2, 3, 4, 7;
 }