More explicit thread checking in SafeBrowsingDatabase.

chrome/browser/safe_browsing/safe_browsing_store_file.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 CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_STORE_FILE_H_
 #define CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_STORE_FILE_H_
 
 #include <set>
 #include <vector>
 
 #include "chrome/browser/safe_browsing/safe_browsing_store.h"
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
+#include "base/threading/non_thread_safe.h"
 
 // Implement SafeBrowsingStore in terms of a flat file.  The file
 // format is pretty literal:
 //
 // int32 magic;             // magic number "validating" file
 // int32 version;           // format version
 //
 // // Counts for the various data which follows the header.
 // uint32 add_chunk_count;  // Chunks seen, including empties.
 // uint32 sub_chunk_count;  // Ditto.
@@ skipping 89 matching lines @@
 // - When the transaction is finished:
 //   - Read the update data from the temp file into memory.
 //   - Overwrite the temp file with new header data.
 //   - Until done:
 //     - Read shards of the original file's data into memory.
 //     - Merge from the update data.
 //     - Write shards to the temp file.
 //   - Delete original file.
 //   - Rename temp file to original filename.
 
-class SafeBrowsingStoreFile : public SafeBrowsingStore {
+class SafeBrowsingStoreFile : public SafeBrowsingStore,
+                              public base::NonThreadSafe {
  public:
   SafeBrowsingStoreFile();
   ~SafeBrowsingStoreFile() override;
 
   void Init(const base::FilePath& filename,
             const base::Closure& corruption_callback) override;
 
   // Delete any on-disk files, including the permanent storage.
   bool Delete() override;
 
@@ skipping 127 matching lines @@
 
   // Tracks whether corruption has already been seen in the current
   // update, so that only one instance is recorded in the stats.
   // TODO(shess): Remove with format-migration support.
   bool corruption_seen_;
 
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingStoreFile);
 };
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_SAFE_BROWSING_STORE_FILE_H_