[Sync] Speed up Javascript node operations

chrome/browser/sync/engine/syncapi.h

 // 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.
 
 // This file defines the "sync API", an interface to the syncer
 // backend that exposes (1) the core functionality of maintaining a consistent
 // local snapshot of a hierarchical object set; (2) a means to transactionally
 // access and modify those objects; (3) a means to control client/server
 // synchronization tasks, namely: pushing local object modifications to a
 // server, pulling nonlocal object modifications from a server to this client,
@@ skipping 953 matching lines @@
   // onNotificationStateChange({ enabled: (boolean) }):
   //   Sent when notifications are enabled or disabled.
   //
   // onIncomingNotification({ changedTypes: (array) }):
   //   Sent when an incoming notification arrives.  |changedTypes|
   //   is a list of sync types (strings) which have changed.
   //
   // The following messages are processed by the returned backend:
   //
   // getNotificationState():
-  //   If there is a parent router, sends the
-  //   onGetNotificationStateFinished(boolean notificationsEnabled)
-  //   event to |sender| via the parent router with whether or not
-  //   notifications are enabled.
+  //   callback(boolean notificationsEnabled):
+  //     notificationsEnabled: whether or not notifications are
+  //     enabled.
   //
   // getRootNode():
-  //   If there is a parent router, sends the
-  //   onGetRootNodeFinished(dictionary nodeInfo) event to |sender|
-  //   via the parent router with information on the root node.
+  //   callback(dictionary nodeInfo):
+  //     nodeInfo: Information on the root node.
   //
-  // getNodeById(string id):
-  //   If there is a parent router, sends the
-  //   onGetNodeByIdFinished(dictionary nodeInfo) event to |sender|
-  //   via the parent router with information on the node with the
-  //   given id (metahandle), if the id is valid and a node with that
-  //   id exists.  Otherwise, calls onGetNodeByIdFinished(null).
+  // getNodesById(array idList):
+  //   idList: A list of IDs as strings.
+  //   callback(array nodeList):
+  //     nodeList: Information on each node for each valid id in
+  //     idList.  Not guaranteed to be in any order.
+  //
+  // getChildNodeIds(string id):
+  //   id: The id of the node for which to return the child node ids.
+  //   callback(array idList):
+  //     idList: The child node IDs of the node with the given id.
   //
   // All other messages are dropped.
   browser_sync::JsBackend* GetJsBackend();
 
   // Status-related getters. Typically GetStatusSummary will suffice, but
   // GetDetailedSyncStatus can be useful for gathering debug-level details of
   // the internals of the sync engine.
   Status::Summary GetStatusSummary() const;
   Status GetDetailedStatus() const;
 
@@ skipping 31 matching lines @@
  private:
   // An opaque pointer to the nested private class.
   SyncInternal* data_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncManager);
 };
 
 }  // namespace sync_api
 
 #endif  // CHROME_BROWSER_SYNC_ENGINE_SYNCAPI_H_