Move proto files back into chrome/browser/policy/proto

chrome/browser/policy/cloud/proto/chrome_extension_policy.proto

-// Copyright (c) 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 enterprise_management;
-
-// Describes how to retrieve policy data for a particular extension. The
-// extension ID is in the |settings_entity_id| field of the PolicyData message
-// that contains the ExternalPolicyData in its |policy_value| field.
-message ExternalPolicyData {
-  // A URL where the policy data can be downloaded from.
-  optional string download_url = 1;
-
-  // SHA-1 hash of the data at |download_url|. This is used to verify the
-  // integrity of the data, and to detect updates on the client side: the client
-  // downloads the data when its local hash does not match |secure_hash|.
-  optional bytes secure_hash = 2;
-
-  // An authentication method that can be used to verify that the client is
-  // authorized to download |download_url|.
-  enum AuthMethod {
-    // No authentication is performed; knowledge of the URL is enough to
-    // authorize its download.
-    NONE = 0;
-
-    // The HTTP GET request sent to |download_url| must include an
-    // "Authorization: " HTTP header of the GoogleDMToken type. Its value is the
-    // same as the DMToken used for the policy fetch.
-    DMTOKEN = 1;
-
-    // The HTTP GET request sent to |download_url| must include an
-    // "Authorization: " HTTP header of the "OAuth" type. Its value is a valid
-    // Google Accounts OAuth access token.
-    OAUTH = 2;
-  }
-
-  // The authentication method that the client must use to fetch |download_url|.
-  optional AuthMethod download_auth_method = 3 [default = NONE];
-}