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

chrome/browser/policy/proto/chromeos/install_attributes.proto

 // Copyright (c) 2011 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 cryptohome;
 
 // This must match install_attributes.proto in the Chromium OS cryptohome
 // repository. Only the fields that are relevant to the browser are present
 // here.
 message SerializedInstallAttributes {
   message Attribute {
     required string name = 1;
     required bytes value = 2;
   }
   repeated Attribute attributes = 2;
 }