[Sync] Add support for performing a GetKey on startup.

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 437 matching lines @@
 
   // Whether to create the mobile bookmarks folder if it's not
   // already created.  Should be set to true only by mobile clients.
   optional bool create_mobile_bookmarks_folder = 1000 [default = false];
 };
 
 message AuthenticateMessage {
   required string auth_token = 1;
 };
 
+message GetEncryptionKeyMessage {

[tim (not reviewing), 2012/07/19 21:42:03]

Comments on the messages + fields.

[Nicolas Zea, 2012/07/24 22:51:24]

Done.

+}
+
+message GetEncryptionKeyResponse {
+  optional bytes key = 1;
+}
+
 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;
+    GET_ENCRYPTION_KEY = 5;
   }
 
   required Contents message_contents = 3;
   optional CommitMessage commit = 4;
   optional GetUpdatesMessage get_updates = 5;
   optional AuthenticateMessage authenticate = 6;
 
   // Request to clear all Chromium data from the server.
   // DEPRECATED - this field was never used in production.
   // optional ClearUserDataMessage clear_user_data = 9;
 
   optional string store_birthday = 7; // Opaque store ID; if it changes, duck!
   // The client sets this if it detects a sync issue. The server will tell it
   // if it should perform a refresh.
   optional bool sync_problem_detected = 8 [default = false];
 
   // Client side state information for debugging purpose.
   // This is only sent on the first getupdates of every sync cycle,
   // as an optimization to save bandwidth.
   optional DebugInfo debug_info = 10;
+
+  optional GetEncryptionKeyMessage get_encryption_key = 11;
 };
 
 message CommitResponse {
   enum ResponseType {
     SUCCESS = 1;
     CONFLICT = 2; // You're out of date; update and check your data
     // TODO(ncarter): What's the difference between RETRY and TRANSIENT_ERROR?
     RETRY = 3; // Someone has a conflicting, non-expired session open
     INVALID_MESSAGE = 4; // What the client sent was invalid, and trying again
                          // won't help.
@@ skipping 122 matching lines @@
   required double target_utilization = 2;
   required double measure_interval_max = 3;
   required double measure_interval_min = 4;
   required double observation_window = 5;
 };
 
 message ClientToServerResponse {
   optional CommitResponse commit = 1;
   optional GetUpdatesResponse get_updates = 2;
   optional AuthenticateResponse authenticate = 3;
-  // DEPRECATED - this field was never used in production.
-  // optional ClearUserDataResponse clear_user_data = 9;
-  optional GetUpdatesMetadataResponse stream_metadata = 10;
-  // If GetUpdatesStreamingResponse is contained in the ClientToServerResponse,
-  // none of the other fields (error_code and etc) will be set.
-  optional GetUpdatesStreamingResponse stream_data = 11;
-
-  message Error {
-    optional SyncEnums.ErrorType error_type = 1 [default = UNKNOWN];
-    optional string error_description       = 2;
-    optional string url                     = 3;
-    optional SyncEnums.Action action        = 4 [default = UNKNOWN_ACTION];
-
-    // Currently only meaningful if |error_type| is throttled. If this field
-    // is absent then the whole client (all datatypes) is throttled.
-    repeated int32 error_data_type_ids = 5;
-  }
-
-  optional Error error = 13;
 
   // Up until protocol_version 24, the default was SUCCESS which made it
   // impossible to add new enum values since older clients would parse any
   // out-of-range value as SUCCESS. Starting with 25, unless explicitly set,
   // the error_code will be UNKNOWN so that clients know when they're
   // out-of-date. Note also that when using protocol_version < 25,
   // TRANSIENT_ERROR is not supported. Instead, the server sends back a HTTP
   // 400 error code. This is deprecated now.
   optional SyncEnums.ErrorType error_code = 4 [default = UNKNOWN];
   optional string error_message = 5;
 
   // Opaque store ID; if it changes, the contents of the client's cache
   // is meaningless to this server.  This happens most typically when
   // you switch from one storage backend instance (say, a test instance)
   // to another (say, the official instance).
   optional string store_birthday = 6;
 
   optional ClientCommand client_command = 7;
   optional ProfilingData profiling_data = 8;
+  // DEPRECATED - this field was never used in production.
+  // optional ClearUserDataResponse clear_user_data = 9;
+  optional GetUpdatesMetadataResponse stream_metadata = 10;
+  // If GetUpdatesStreamingResponse is contained in the ClientToServerResponse,
+  // none of the other fields (error_code and etc) will be set.
+  optional GetUpdatesStreamingResponse stream_data = 11;
 
   // The data types whose storage has been migrated.  Present when the value of
   // error_code is MIGRATION_DONE.
   repeated int32 migrated_data_type_id = 12;
+
+  message Error {
+    optional SyncEnums.ErrorType error_type = 1 [default = UNKNOWN];
+    optional string error_description       = 2;
+    optional string url                     = 3;
+    optional SyncEnums.Action action        = 4 [default = UNKNOWN_ACTION];
+
+    // Currently only meaningful if |error_type| is throttled. If this field
+    // is absent then the whole client (all datatypes) is throttled.
+    repeated int32 error_data_type_ids = 5;
+  }
+  optional Error error = 13;
+
+  optional GetEncryptionKeyResponse get_encryption_key = 14;
 };