Fetch extension blacklist states from SafeBrowsing server

chrome/common/safe_browsing/crx_info.proto

+// Copyright 2013 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 extensions;
+
+// This is used to request more information on blacklisted CRX packages. The
+// client maintains a local cache of blacklisted ids, and makes requests to our
+// server to get more information, such as the blacklist type.
+message ClientCRXListInfoRequest {
+  // ID of the CRX package.
+  required string id = 1;
+
+  // Locale of the device, eg en, en_US.
+  optional string locale = 2;
+}
+
+message ClientCRXListInfoResponse {
+  enum Verdict {
+    NOT_IN_BLACKLIST = 0;
+    MALWARE = 1;
+    SECURITY_VULNERABILITY = 2;
+    CWS_POLICY_VIOLATION = 3;
+    POTENTIALLY_UNWANTED = 4;
+  }
+  // Although listed as optional, this is required.
+  optional Verdict verdict = 1 [default=NOT_IN_BLACKLIST];
+
+  message UserMessage {
+    // If present, will be appended to disable reason in the details page. We
+    // could use this to send a URL to a blogpost or help article.
+    optional string detail_message = 1;
+  }
+  optional UserMessage user_message = 2;
+}