Move SafeBrowsing to the blocking pool via an experiment.

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"
+#include "base/sequenced_task_runner.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,
-                              public base::NonThreadSafe {
+class SafeBrowsingStoreFile : public SafeBrowsingStore {
  public:
-  SafeBrowsingStoreFile();
+  explicit SafeBrowsingStoreFile(
+      const scoped_refptr<const base::SequencedTaskRunner>& task_runner);
   ~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;
 
   // Get all add hash prefixes and full-length hashes, respectively, from
   // the store.
@@ skipping 36 matching lines @@
   // |filename|.  Exported for unit tests.
   static const base::FilePath TemporaryFileForFilename(
       const base::FilePath& filename) {
     return base::FilePath(filename.value() + FILE_PATH_LITERAL("_new"));
   }
 
   // Delete any on-disk files, including the permanent storage.
   static bool DeleteStore(const base::FilePath& basename);
 
  private:
+  // Checks whether the current thread is part of the sequenced task runner
+  // this object was initialized with.
+  bool CalledOnValidThread();
+
   // Does the actual update for FinishUpdate(), so that FinishUpdate() can clean
   // up correctly in case of error.
   virtual bool DoUpdate(safe_browsing::PrefixSetBuilder* builder,
                         std::vector<SBAddFullHash>* add_full_hashes_result);
 
   // Some very lucky users have an original-format file still in their
   // profile.  Check for it and delete, recording a histogram for the
   // result (no histogram for not-found).  Logically this
   // would make more sense at the SafeBrowsingDatabase level, but
   // practically speaking that code doesn't touch files directly.
@@ skipping 26 matching lines @@
   // Clear all buffers used during update.
   void ClearUpdateBuffers() {
     ClearChunkBuffers();
     chunks_written_ = 0;
     std::set<int32>().swap(add_chunks_cache_);
     std::set<int32>().swap(sub_chunks_cache_);
     base::hash_set<int32>().swap(add_del_cache_);
     base::hash_set<int32>().swap(sub_del_cache_);
   }
 
+  // The sequenced task runner for this object, used to verify that its state
+  // is only ever accessed from the runner.
+  scoped_refptr<const base::SequencedTaskRunner> task_runner_;
+
   // Buffers for collecting data between BeginChunk() and
   // FinishChunk().
   SBAddPrefixes add_prefixes_;
   SBSubPrefixes sub_prefixes_;
   std::vector<SBAddFullHash> add_hashes_;
   std::vector<SBSubFullHash> sub_hashes_;
 
   // Count of chunks collected in |new_file_|.
   int chunks_written_;
 
@@ skipping 23 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_