[Sync] Add context proto and directory support

sync/protocol/sync.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.
 //
 // Sync protocol for communication between sync client and server.
 
 // Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
 // any fields in this file.
 
 syntax = "proto2";
@@ skipping 390 matching lines @@
   optional string cache_guid = 2;
 
   repeated ChromiumExtensionsActivity extensions_activity = 3;
 
   // The configuration of this client at commit time. Used by the server to
   // make commit-time decisions about how to process datatypes that might
   // involve server-side interaction, and e.g require explicit user intent for
   // syncing a particular data type regardless of whether a commit for that
   // datatype is currently being sent up.
   optional ClientConfigParams config_params = 4;
+
+  // Set of optional per-client datatype contexts.
+  repeated DataTypeContext client_contexts = 5;
 };
 
 // This message communicates additional per-type information related to
 // requests with origin GU_TRIGGER.  This message is not relevant when any
 // other origin value is used.
 // Introduced in M29.
 message GetUpdateTriggers {
   // An opaque-to-the-client string of bytes, received through a notification,
   // that the server may interpret as a hint about the location of the latest
   // version of the data for this type.
@@ skipping 198 matching lines @@
   optional bool create_mobile_bookmarks_folder = 1000 [default = false];
 
   // This value is an updated version of the GetUpdatesCallerInfo's
   // GetUpdatesSource.  It describes the reason for the GetUpdate request.
   // Introduced in M29.
   optional SyncEnums.GetUpdatesOrigin get_updates_origin = 9;
 
   // Whether this GU also serves as a retry GU. Any GU that happens after
   // retry timer timeout is a retry GU effectively.
   optional bool is_retry = 10 [default = false];
+
+  // Set of optional per-client datatype contexts.

[maniscalco, 2014/04/03 16:59:37]

Just for my own benefit... I assume that you're using the term set here
intentionally.  I.e. the client promises not to send a list of contexts with
duplicate types.  Or does it make sense to ever send (or receive) two contexts
with the same type?

[Nicolas Zea, 2014/04/03 21:01:11]

No, there should only be one per type.

+  repeated DataTypeContext client_contexts = 11;

[maniscalco, 2014/04/03 16:59:37]

I don't think we've been consistent, but going forward what's our naming
convention for repeated fields, singular or plural?

[Nicolas Zea, 2014/04/03 21:01:11]

I don't think we have one. I try to use plural though.

 };
 
 message AuthenticateMessage {
   required string auth_token = 1;
 };
 
 message ClearUserDataMessage {
 };
 
 message ClearUserDataResponse {
@@ skipping 23 matching lines @@
   // Flag to indicate if the client has detected hierarchy conflcits.  The flag
   // is left unset if update application has not been attempted yet.
   //
   // The server should attempt to resolve any hierarchy conflicts when this flag
   // is set.  The client may not assume that any particular action will be
   // taken.  There is no guarantee the problem will be addressed in a reasonable
   // amount of time.
   optional bool hierarchy_conflict_detected = 1;
 }
 
+// A single datatype's sync context. Allows the datatype to pass along
+// datatype specific information with its own server backend.
+message DataTypeContext {
+  // The type this context is associated with.
+  optional int32 type = 1;

[maniscalco, 2014/04/03 16:59:37]

Elsewhere in this file I see "data_type_id".  Is this the same thing?  If so,
consider renaming to data_type_id so it's clear that it's the same thing.

[Nicolas Zea, 2014/04/03 21:01:11]

Done.

+  // The context for the datatype.
+  optional bytes context = 2;
+  // The version of the context.
+  optional int64 version = 3;
+}
+
 message ClientToServerMessage {
   required string share = 1;
   optional int32 protocol_version = 2 [default = 31];
   enum Contents {
     COMMIT = 1;
     GET_UPDATES = 2;
     AUTHENTICATE = 3;
     CLEAR_DATA = 4;
   }
 
@@ skipping 143 matching lines @@
   //
   // Progress markers in the context of a response will never have the
   // |timestamp_token_for_migration| field set.
   repeated DataTypeProgressMarker new_progress_marker = 5;
 
   // The current encryption keys associated with this account. Will be set if
   // the GetUpdatesMessage in the request had need_encryption_key == true or
   // the server has updated the set of encryption keys (e.g. due to a key
   // rotation).
   repeated bytes encryption_keys = 6;
+
+  // Set of optional datatype contexts server mutations.
+  repeated DataTypeContext context_mutations = 7;
 };
 
 // The metadata response for GetUpdatesMessage.  This response is sent when
 // streaming is set to true in the request.  It is prefixed with a length
 // delimiter, which is encoded in varint.
 message GetUpdatesMetadataResponse {
   // Approximate count of changes remaining.  Detailed comment is available in
   // GetUpdatesResponse.
   optional int64 changes_remaining = 1;
 
@@ skipping 79 matching lines @@
     // is absent then the whole client (all datatypes) is throttled.
     repeated int32 error_data_type_ids = 5;
   }
   optional Error error = 13;
 
   // The new per-client state for this client. If set, should be persisted and
   // sent with any subsequent ClientToServerMessages.
   optional ChipBag new_bag_of_chips = 14;
 };