Add comment explaining fix and added explicit HistoryService dependency in predictor.

chrome/browser/predictors/predictor_database.cc

 // 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.
 
 #include "chrome/browser/predictors/predictor_database.h"
 
 #include "base/bind.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
@@ skipping 52 matching lines @@
     : db_path_(profile->GetPath().Append(kPredictorDatabaseName)),
       autocomplete_table_(new AutocompleteActionPredictorTable()),
       resource_prefetch_tables_(new ResourcePrefetchPredictorTables()) {
 }
 
 PredictorDatabaseInternal::~PredictorDatabaseInternal() {
 }
 
 void PredictorDatabaseInternal::Initialize() {
   CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::DB));
-
   db_.set_exclusive_locking();
   bool success = db_.Open(db_path_);
 
   if (!success)
     return;
 
   autocomplete_table_->Initialize(&db_);
   resource_prefetch_tables_->Initialize(&db_);
 
   LogDatabaseStats();
@@ skipping 40 matching lines @@
 scoped_refptr<ResourcePrefetchPredictorTables>
     PredictorDatabase::resource_prefetch_tables() {
   return db_->resource_prefetch_tables_;
 }
 
 sql::Connection* PredictorDatabase::GetDatabase() {
   return &db_->db_;
 }
 
 }  // namespace predictors