contacts: Add GDataContactsService.

chrome/browser/chromeos/contacts/contact.proto

 // Copyright (c) 2012 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.
 //
 // Protocol buffer definitions for the user's contacts.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package contacts;
 
 // A contact, roughly based on the GData Contact kind:
 // https://developers.google.com/gdata/docs/2.0/elements#gdContactKind
 // All strings are UTF-8.
 message Contact {
   // Next ID to use: 15
 
   // Provider-assigned unique identifier.
   optional string provider_id = 1;
 
-  // Last time at which this contact was updated within the upstream provider.
+  // Last time at which this contact was updated within the upstream provider,
+  // as given by base::Time::ToInternalValue().
   optional int64 update_time = 2;
 
   // Has the contact been deleted recently within the upstream provider?
   optional bool deleted = 3 [default = false];
 
   // Taken from https://developers.google.com/gdata/docs/2.0/elements#gdName.
   optional string full_name = 4;
   optional string given_name = 5;
   optional string additional_name = 6;
   optional string family_name = 7;
@@ skipping 56 matching lines @@
       ICQ = 6;
       JABBER = 7;
       OTHER = 8;
     }
     optional Protocol protocol = 2 [default = OTHER];
     optional AddressType type = 3;
     optional bool primary = 4 [default = false];
   }
   repeated InstantMessagingAddress instant_messaging_addresses = 14;
 }