Add additional error logging to investigate Autocomplete Sync failures.

sync/internal_api/write_node.h

 // 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.
 
 #ifndef SYNC_INTERNAL_API_WRITE_NODE_H_
 #define SYNC_INTERNAL_API_WRITE_NODE_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 28 matching lines @@
 }
 
 namespace sync_api {
 
 class WriteTransaction;
 
 // WriteNode extends BaseNode to add mutation, and wraps
 // syncable::MutableEntry. A WriteTransaction is needed to create a WriteNode.
 class WriteNode : public BaseNode {
  public:
+  enum InitUniqueByCreationResult {
+    INIT_SUCCESS,
+    // The tag passed into this method was empty.
+    INIT_FAILED_EMPTY_TAG,
+    // An entry with this tag already exists.
+    INIT_FAILED_ENTRY_ALREADY_EXISTS,
+    // The constructor for a new MutableEntry with the specified data failed.
+    INIT_FAILED_COULD_NOT_CREATE_ENTRY,
+    // Setting the predecessor failed
+    INIT_FAILED_SET_PREDECESSOR,
+  };
+
   // Create a WriteNode using the given transaction.
   explicit WriteNode(WriteTransaction* transaction);
   virtual ~WriteNode();
 
   // A client must use one (and only one) of the following Init variants to
   // populate the node.
 
   // BaseNode implementation.
   virtual InitByLookupResult InitByIdLookup(int64 id) OVERRIDE;
   virtual InitByLookupResult InitByClientTagLookup(
       syncable::ModelType model_type,
       const std::string& tag) OVERRIDE;
 
   // Create a new node with the specified parent and predecessor.  |model_type|
   // dictates the type of the item, and controls which EntitySpecifics proto
   // extension can be used with this item.  Use a NULL |predecessor|
   // to indicate that this is to be the first child.
   // |predecessor| must be a child of |new_parent| or NULL. Returns false on
   // failure.
   bool InitByCreation(syncable::ModelType model_type,
                       const BaseNode& parent,
                       const BaseNode* predecessor);
 
   // Create nodes using this function if they're unique items that
   // you want to fetch using client_tag. Note that the behavior of these
   // items is slightly different than that of normal items.
   // Most importantly, if it exists locally, this function will
   // actually undelete it
   // Client unique tagged nodes must NOT be folders.
-  bool InitUniqueByCreation(syncable::ModelType model_type,
-                            const BaseNode& parent,
-                            const std::string& client_tag);
+  InitUniqueByCreationResult InitUniqueByCreation(
+      syncable::ModelType model_type,
+      const BaseNode& parent,
+      const std::string& client_tag);
 
   // Each server-created permanent node is tagged with a unique string.
   // Look up the node with the particular tag.  If it does not exist,
   // return false.
   InitByLookupResult InitByTagLookup(const std::string& tag);
 
   // These Set() functions correspond to the Get() functions of BaseNode.
   void SetIsFolder(bool folder);
   void SetTitle(const std::wstring& title);
 
@@ skipping 90 matching lines @@
 
   // The sync API transaction that is the parent of this node.
   WriteTransaction* transaction_;
 
   DISALLOW_COPY_AND_ASSIGN(WriteNode);
 };
 
 }  // namespace sync_api
 
 #endif  // SYNC_INTERNAL_API_WRITE_NODE_H_