Convert utility process extension Unpacker IPC to mojo

extensions/common/manifest_location.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;
+
+// What an extension was loaded from.
+// NOTE: These values are stored as integers in the preferences and used
+// in histograms so don't remove or reorder existing items.  Just append
+// to the end.
+enum ManifestLocation {
+  INVALID_LOCATION,
+  INTERNAL,           // A crx file from the internal Extensions directory.
+  EXTERNAL_PREF,      // A crx file from an external directory (via prefs).
+  EXTERNAL_REGISTRY,  // A crx file from an external directory (via eg the
+                      // registry on Windows).
+  UNPACKED,           // From loading an unpacked extension from the
+                      // extensions settings page.
+  COMPONENT,          // An integral component of Chrome itself, which
+                      // happens to be implemented as an extension. We don't
+                      // show these in the management UI.
+  EXTERNAL_PREF_DOWNLOAD,    // A crx file from an external directory (via
+                             // prefs), installed from an update URL.
+  EXTERNAL_POLICY_DOWNLOAD,  // A crx file from an external directory (via
+                             // admin policies), installed from an update URL.
+  COMMAND_LINE,              // --load-extension.
+  EXTERNAL_POLICY,     // A crx file from an external directory (via admin
+                       // policies), cached locally and installed from the
+                       // cache.
+  EXTERNAL_COMPONENT,  // Similar to COMPONENT in that it's considered an
+                       // internal implementation detail of chrome, but
+                       // installed from an update URL like the *DOWNLOAD ones.
+};