[Sync] Make DirectoryBackingStore's db_ private.

sync/syncable/on_disk_directory_backing_store.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 "sync/syncable/on_disk_directory_backing_store.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/metrics/histogram.h"
 #include "sync/syncable/syncable-inl.h"
@@ skipping 20 matching lines @@
 }
 
 OnDiskDirectoryBackingStore::~OnDiskDirectoryBackingStore() { }
 
 DirOpenResult OnDiskDirectoryBackingStore::TryLoad(
     Directory::MetahandlesMap* handles_map,
     JournalIndex* delete_journals,
     MetahandleSet* metahandles_to_purge,
     Directory::KernelLoadInfo* kernel_load_info) {
   DCHECK(CalledOnValidThread());
-  if (!db_->is_open()) {
-    if (!db_->Open(backing_filepath_))
+
+  if (!IsOpen()) {
+    if (!Open(backing_filepath_))
       return FAILED_OPEN_DATABASE;
   }
 
   if (!InitializeTables())
     return FAILED_OPEN_DATABASE;
 
   if (!LoadEntries(handles_map, metahandles_to_purge))
     return FAILED_DATABASE_CORRUPT;
   if (!LoadDeleteJournals(delete_journals))
     return FAILED_DATABASE_CORRUPT;
@@ skipping 50 matching lines @@
   // immediately so a developer can investigate.
   //
   // Developers: If you're not interested in debugging this right now, just move
   // aside the 'Sync Data' directory in your profile.  This is similar to what
   // the code would do if this DCHECK were disabled.
   NOTREACHED() << "Crashing to preserve corrupt sync database";
 }
 
 }  // namespace syncable
 }  // namespace syncer