Move SafeBrowsing to the blocking pool via an experiment.

chrome/browser/safe_browsing/safe_browsing_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/safe_browsing/safe_browsing_database.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/bind.h"
@@ skipping 299 matching lines @@
   // Find full-hash matches.
   std::vector<SBFullHashResult>& cached_hashes = cached_result.full_hashes;
   for (size_t i = 0; i < cached_hashes.size(); ++i) {
     if (SBFullHashEqual(full_hash, cached_hashes[i].hash))
       results->push_back(cached_hashes[i]);
   }
 
   return true;
 }
 
+SafeBrowsingStoreFile* CreateStore(
+    bool enable,
+    scoped_refptr<base::SequencedTaskRunner> task_runner) {
+  if (!enable)
+    return nullptr;
+  return new SafeBrowsingStoreFile(task_runner);
+}
+
 }  // namespace
 
 // The default SafeBrowsingDatabaseFactory.
 class SafeBrowsingDatabaseFactoryImpl : public SafeBrowsingDatabaseFactory {
  public:
   SafeBrowsingDatabase* CreateSafeBrowsingDatabase(
+      scoped_refptr<base::SequencedTaskRunner> db_task_runner,
       bool enable_download_protection,
       bool enable_client_side_whitelist,
       bool enable_download_whitelist,
       bool enable_extension_blacklist,
       bool enable_side_effect_free_whitelist,
       bool enable_ip_blacklist,
       bool enable_unwanted_software_list) override {
     return new SafeBrowsingDatabaseNew(
-        new SafeBrowsingStoreFile,  // browse_store
-        enable_download_protection ? new SafeBrowsingStoreFile : NULL,
-        enable_client_side_whitelist ? new SafeBrowsingStoreFile : NULL,
-        enable_download_whitelist ? new SafeBrowsingStoreFile : NULL,
-        new SafeBrowsingStoreFile,  // inclusion_whitelist_store
-        enable_extension_blacklist ? new SafeBrowsingStoreFile : NULL,
-        enable_side_effect_free_whitelist ? new SafeBrowsingStoreFile : NULL,
-        enable_ip_blacklist ? new SafeBrowsingStoreFile : NULL,
-        enable_unwanted_software_list ? new SafeBrowsingStoreFile : NULL);
+        db_task_runner, CreateStore(true, db_task_runner),  // browse_store
+        CreateStore(enable_download_protection, db_task_runner),
+        CreateStore(enable_client_side_whitelist, db_task_runner),
+        CreateStore(enable_download_whitelist, db_task_runner),
+        CreateStore(true, db_task_runner),  // inclusion_whitelist_store
+        CreateStore(enable_extension_blacklist, db_task_runner),
+        CreateStore(enable_side_effect_free_whitelist, db_task_runner),
+        CreateStore(enable_ip_blacklist, db_task_runner),
+        CreateStore(enable_unwanted_software_list, db_task_runner));
   }
 
   SafeBrowsingDatabaseFactoryImpl() { }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingDatabaseFactoryImpl);
 };
 
 // static
 SafeBrowsingDatabaseFactory* SafeBrowsingDatabase::factory_ = NULL;
 
-// Factory method, non-thread safe. Caller has to make sure this is called
-// on SafeBrowsing Thread.
+// Factory method, should be called on the Safe Browsing sequenced task runner,
+// which is also passed to the function as |current_task_runner|.
 // TODO(shess): There's no need for a factory any longer.  Convert
 // SafeBrowsingDatabaseNew to SafeBrowsingDatabase, and have Create()
 // callers just construct things directly.
 SafeBrowsingDatabase* SafeBrowsingDatabase::Create(
+    scoped_refptr<base::SequencedTaskRunner> current_task_runner,
     bool enable_download_protection,
     bool enable_client_side_whitelist,
     bool enable_download_whitelist,
     bool enable_extension_blacklist,
     bool enable_side_effect_free_whitelist,
     bool enable_ip_blacklist,
     bool enable_unwanted_software_list) {
+  DCHECK(current_task_runner->RunsTasksOnCurrentThread());
   if (!factory_)
     factory_ = new SafeBrowsingDatabaseFactoryImpl();
-  return factory_->CreateSafeBrowsingDatabase(enable_download_protection,
-                                              enable_client_side_whitelist,
-                                              enable_download_whitelist,
-                                              enable_extension_blacklist,
-                                              enable_side_effect_free_whitelist,
-                                              enable_ip_blacklist,
-                                              enable_unwanted_software_list);
+  return factory_->CreateSafeBrowsingDatabase(
+      current_task_runner, enable_download_protection,
+      enable_client_side_whitelist, enable_download_whitelist,
+      enable_extension_blacklist, enable_side_effect_free_whitelist,
+      enable_ip_blacklist, enable_unwanted_software_list);
 }
 
 SafeBrowsingDatabase::~SafeBrowsingDatabase() {
 }
 
 // static
 base::FilePath SafeBrowsingDatabase::BrowseDBFilename(
     const base::FilePath& db_base_filename) {
   return base::FilePath(db_base_filename.value() + kBrowseDBFile);
 }
@@ skipping 53 matching lines @@
 }
 
 // static
 base::FilePath SafeBrowsingDatabase::UnwantedSoftwareDBFilename(
     const base::FilePath& db_filename) {
   return base::FilePath(db_filename.value() + kUnwantedSoftwareDBFile);
 }
 
 SafeBrowsingStore* SafeBrowsingDatabaseNew::GetStore(const int list_id) {
   // Stores are not thread safe.
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   if (list_id == safe_browsing_util::PHISH ||
       list_id == safe_browsing_util::MALWARE) {
     return browse_store_.get();
   } else if (list_id == safe_browsing_util::BINURL) {
     return download_store_.get();
   } else if (list_id == safe_browsing_util::CSDWHITELIST) {
     return csd_whitelist_store_.get();
   } else if (list_id == safe_browsing_util::DOWNLOADWHITELIST) {
     return download_whitelist_store_.get();
@@ skipping 68 matching lines @@
     DONT_LOCK_ON_MAIN_THREAD
   };
 
   ReadTransaction(const ThreadSafeStateManager* outer,
                   AutoLockRequirement auto_lock_requirement)
       : outer_(outer) {
     DCHECK(outer_);
     if (auto_lock_requirement == AutoLockRequirement::LOCK)
       transaction_lock_.reset(new base::AutoLock(outer_->lock_));
     else
-      DCHECK(outer_->thread_checker_.CalledOnValidThread());
+      DCHECK(outer_->db_task_runner_->RunsTasksOnCurrentThread());
   }
 
   const ThreadSafeStateManager* outer_;
   scoped_ptr<base::AutoLock> transaction_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadTransaction);
 };
 
 class SafeBrowsingDatabaseNew::ThreadSafeStateManager::WriteTransaction {
  public:
@@ skipping 35 matching lines @@
 
   void clear_prefix_gethash_cache() { outer_->prefix_gethash_cache_.clear(); }
 
  private:
   // Only ThreadSafeStateManager is allowed to build a WriteTransaction.
   friend class ThreadSafeStateManager;
 
   explicit WriteTransaction(ThreadSafeStateManager* outer)
       : outer_(outer), transaction_lock_(outer_->lock_) {
     DCHECK(outer_);
-    DCHECK(outer_->thread_checker_.CalledOnValidThread());
+    DCHECK(outer_->db_task_runner_->RunsTasksOnCurrentThread());
   }
 
   SBWhitelist* SBWhitelistForId(SBWhitelistId id) {
     switch (id) {
       case SBWhitelistId::CSD:
         return &outer_->csd_whitelist_;
       case SBWhitelistId::DOWNLOAD:
         return &outer_->download_whitelist_;
       case SBWhitelistId::INCLUSION:
         return &outer_->inclusion_whitelist_;
     }
     NOTREACHED();
     return nullptr;
   }
 
   ThreadSafeStateManager* outer_;
   base::AutoLock transaction_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(WriteTransaction);
 };
 
 SafeBrowsingDatabaseNew::ThreadSafeStateManager::ThreadSafeStateManager(
-    const base::ThreadChecker& thread_checker)
-    : thread_checker_(thread_checker) {
+    scoped_refptr<const base::SequencedTaskRunner> db_task_runner)
+    : db_task_runner_(db_task_runner) {
 }
 
 SafeBrowsingDatabaseNew::ThreadSafeStateManager::~ThreadSafeStateManager() {
 }
 
+SafeBrowsingDatabaseNew::DatabaseStateManager::DatabaseStateManager(
+    scoped_refptr<const base::SequencedTaskRunner> db_task_runner)
+    : db_task_runner_(db_task_runner),
+      corruption_detected_(false),
+      change_detected_(false) {
+}
+
+SafeBrowsingDatabaseNew::DatabaseStateManager::~DatabaseStateManager() {
+}
+
 scoped_ptr<SafeBrowsingDatabaseNew::ReadTransaction>
 SafeBrowsingDatabaseNew::ThreadSafeStateManager::BeginReadTransaction() {
   return make_scoped_ptr(
       new ReadTransaction(this, ReadTransaction::AutoLockRequirement::LOCK));
 }
 
 scoped_ptr<SafeBrowsingDatabaseNew::ReadTransaction> SafeBrowsingDatabaseNew::
     ThreadSafeStateManager::BeginReadTransactionNoLockOnMainThread() {
   return make_scoped_ptr(new ReadTransaction(
       this, ReadTransaction::AutoLockRequirement::DONT_LOCK_ON_MAIN_THREAD));
 }
 
 scoped_ptr<SafeBrowsingDatabaseNew::WriteTransaction>
 SafeBrowsingDatabaseNew::ThreadSafeStateManager::BeginWriteTransaction() {
   return make_scoped_ptr(new WriteTransaction(this));
 }
 
-SafeBrowsingDatabaseNew::SafeBrowsingDatabaseNew()
-    : SafeBrowsingDatabaseNew(new SafeBrowsingStoreFile,  // browse_store
-                              NULL,    // download_store
-                              NULL,    // csd_whitelist_store
-                              NULL,    // download_whitelist_store
-                              NULL,    // inclusion_whitelist_store
-                              NULL,    // extension_blacklist_store
-                              NULL,    // side_effect_free_whitelist_store
-                              NULL,    // ip_blacklist_store
-                              NULL) {  // unwanted_software_store
-  DCHECK(browse_store_.get());
-  DCHECK(!download_store_.get());
-  DCHECK(!csd_whitelist_store_.get());
-  DCHECK(!download_whitelist_store_.get());
-  DCHECK(!inclusion_whitelist_store_.get());
-  DCHECK(!extension_blacklist_store_.get());
-  DCHECK(!side_effect_free_whitelist_store_.get());
-  DCHECK(!ip_blacklist_store_.get());
-  DCHECK(!unwanted_software_store_.get());
-}
-
 SafeBrowsingDatabaseNew::SafeBrowsingDatabaseNew(
+    scoped_refptr<base::SequencedTaskRunner> db_task_runner,
     SafeBrowsingStore* browse_store,
     SafeBrowsingStore* download_store,
     SafeBrowsingStore* csd_whitelist_store,
     SafeBrowsingStore* download_whitelist_store,
     SafeBrowsingStore* inclusion_whitelist_store,
     SafeBrowsingStore* extension_blacklist_store,
     SafeBrowsingStore* side_effect_free_whitelist_store,
     SafeBrowsingStore* ip_blacklist_store,
     SafeBrowsingStore* unwanted_software_store)
-    : state_manager_(thread_checker_),
-      db_state_manager_(thread_checker_),
+    : db_task_runner_(db_task_runner),
+      state_manager_(db_task_runner_),
+      db_state_manager_(db_task_runner_),
       browse_store_(browse_store),
       download_store_(download_store),
       csd_whitelist_store_(csd_whitelist_store),
       download_whitelist_store_(download_whitelist_store),
       inclusion_whitelist_store_(inclusion_whitelist_store),
       extension_blacklist_store_(extension_blacklist_store),
       side_effect_free_whitelist_store_(side_effect_free_whitelist_store),
       ip_blacklist_store_(ip_blacklist_store),
       unwanted_software_store_(unwanted_software_store),
       reset_factory_(this) {
   DCHECK(browse_store_.get());
 }
 
 SafeBrowsingDatabaseNew::~SafeBrowsingDatabaseNew() {
   // The DCHECK is disabled due to crbug.com/338486 .
-  // DCHECK(thread_checker_.CalledOnValidThread());
+  // DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 }
 
 void SafeBrowsingDatabaseNew::Init(const base::FilePath& filename_base) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   db_state_manager_.init_filename_base(filename_base);
 
   // TODO(shess): The various stores are really only necessary while doing
   // updates (see |UpdateFinished()|) or when querying a store directly (see
   // |ContainsDownloadUrl()|).
   // The store variables are also tested to see if a list is enabled.  Perhaps
   // the stores could be refactored into an update object so that they are only
   // live in memory while being actively used.  The sense of enabled probably
   // belongs in protocol_manager or database_manager.
@@ skipping 129 matching lines @@
     std::vector<SBAddFullHash> full_hashes;
     if (ip_blacklist_store_->GetAddFullHashes(&full_hashes)) {
       LoadIpBlacklist(full_hashes);
     } else {
       LoadIpBlacklist(std::vector<SBAddFullHash>());  // Clear the list.
     }
   }
 }
 
 bool SafeBrowsingDatabaseNew::ResetDatabase() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // Delete files on disk.
   // TODO(shess): Hard to see where one might want to delete without a
   // reset.  Perhaps inline |Delete()|?
   if (!Delete())
     return false;
 
   // Reset objects in memory.
   scoped_ptr<WriteTransaction> txn = state_manager_.BeginWriteTransaction();
   txn->clear_prefix_gethash_cache();
@@ skipping 79 matching lines @@
   std::sort(prefix_hits->begin(), prefix_hits->end());
   prefix_hits->erase(std::unique(prefix_hits->begin(), prefix_hits->end()),
                      prefix_hits->end());
 
   return !prefix_hits->empty() || !cache_hits->empty();
 }
 
 bool SafeBrowsingDatabaseNew::ContainsDownloadUrl(
     const std::vector<GURL>& urls,
     std::vector<SBPrefix>* prefix_hits) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // Ignore this check when download checking is not enabled.
   if (!download_store_.get())
     return false;
 
   std::vector<SBPrefix> prefixes;
   GetDownloadUrlPrefixes(urls, &prefixes);
   return MatchAddPrefixes(download_store_.get(),
                           safe_browsing_util::BINURL % 2,
                           prefixes,
@@ skipping 14 matching lines @@
 
 bool SafeBrowsingDatabaseNew::ContainsInclusionWhitelistedUrl(const GURL& url) {
   std::vector<SBFullHash> full_hashes;
   UrlToFullHashes(url, true, &full_hashes);
   return ContainsWhitelistedHashes(SBWhitelistId::INCLUSION, full_hashes);
 }
 
 bool SafeBrowsingDatabaseNew::ContainsExtensionPrefixes(
     const std::vector<SBPrefix>& prefixes,
     std::vector<SBPrefix>* prefix_hits) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   if (!extension_blacklist_store_)
     return false;
 
   return MatchAddPrefixes(extension_blacklist_store_.get(),
                           safe_browsing_util::EXTENSIONBLACKLIST % 2,
                           prefixes,
                           prefix_hits);
 }
 
@@ skipping 76 matching lines @@
     }
   }
   return false;
 }
 
 // Helper to insert add-chunk entries.
 void SafeBrowsingDatabaseNew::InsertAddChunk(
     SafeBrowsingStore* store,
     const safe_browsing_util::ListType list_id,
     const SBChunkData& chunk_data) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(store);
 
   // The server can give us a chunk that we already have because
   // it's part of a range.  Don't add it again.
   const int chunk_id = chunk_data.ChunkNumber();
   const int encoded_chunk_id = EncodeChunkId(chunk_id, list_id);
   if (store->CheckAddChunk(encoded_chunk_id))
     return;
 
   store->SetAddChunk(encoded_chunk_id);
   if (chunk_data.IsPrefix()) {
     const size_t c = chunk_data.PrefixCount();
     for (size_t i = 0; i < c; ++i) {
       store->WriteAddPrefix(encoded_chunk_id, chunk_data.PrefixAt(i));
     }
   } else {
     const size_t c = chunk_data.FullHashCount();
     for (size_t i = 0; i < c; ++i) {
       store->WriteAddHash(encoded_chunk_id, chunk_data.FullHashAt(i));
     }
   }
 }
 
 // Helper to insert sub-chunk entries.
 void SafeBrowsingDatabaseNew::InsertSubChunk(
     SafeBrowsingStore* store,
     const safe_browsing_util::ListType list_id,
     const SBChunkData& chunk_data) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(store);
 
   // The server can give us a chunk that we already have because
   // it's part of a range.  Don't add it again.
   const int chunk_id = chunk_data.ChunkNumber();
   const int encoded_chunk_id = EncodeChunkId(chunk_id, list_id);
   if (store->CheckSubChunk(encoded_chunk_id))
     return;
 
   store->SetSubChunk(encoded_chunk_id);
@@ skipping 12 matching lines @@
       const int encoded_add_chunk_id = EncodeChunkId(add_chunk_id, list_id);
       store->WriteSubHash(encoded_chunk_id, encoded_add_chunk_id,
                           chunk_data.FullHashAt(i));
     }
   }
 }
 
 void SafeBrowsingDatabaseNew::InsertChunks(
     const std::string& list_name,
     const std::vector<SBChunkData*>& chunks) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   if (db_state_manager_.corruption_detected() || chunks.empty())
     return;
 
   const base::TimeTicks before = base::TimeTicks::Now();
 
   // TODO(shess): The caller should just pass list_id.
   const safe_browsing_util::ListType list_id =
       safe_browsing_util::GetListId(list_name);
 
@@ skipping 14 matching lines @@
       NOTREACHED();
     }
   }
   store->FinishChunk();
 
   UMA_HISTOGRAM_TIMES("SB2.ChunkInsert", base::TimeTicks::Now() - before);
 }
 
 void SafeBrowsingDatabaseNew::DeleteChunks(
     const std::vector<SBChunkDelete>& chunk_deletes) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   if (db_state_manager_.corruption_detected() || chunk_deletes.empty())
     return;
 
   const std::string& list_name = chunk_deletes.front().list_name;
   const safe_browsing_util::ListType list_id =
       safe_browsing_util::GetListId(list_name);
 
   SafeBrowsingStore* store = GetStore(list_id);
   if (!store) return;
@@ skipping 30 matching lines @@
   // Insert any fullhash hits. Note that there may be one, multiple, or no
   // fullhashes for any given entry in |prefixes|.
   for (size_t i = 0; i < full_hits.size(); ++i) {
     const SBPrefix prefix = full_hits[i].hash.prefix;
     (*prefix_gethash_cache)[prefix].full_hashes.push_back(full_hits[i]);
   }
 }
 
 bool SafeBrowsingDatabaseNew::UpdateStarted(
     std::vector<SBListChunkRanges>* lists) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(lists);
 
   // If |BeginUpdate()| fails, reset the database.
   if (!browse_store_->BeginUpdate()) {
     RecordFailure(FAILURE_BROWSE_DATABASE_UPDATE_BEGIN);
     HandleCorruptDatabase();
     return false;
   }
 
   if (download_store_.get() && !download_store_->BeginUpdate()) {
@@ skipping 85 matching lines @@
   UpdateChunkRangesForList(unwanted_software_store_.get(),
                            safe_browsing_util::kUnwantedUrlList,
                            lists);
 
   db_state_manager_.reset_corruption_detected();
   db_state_manager_.reset_change_detected();
   return true;
 }
 
 void SafeBrowsingDatabaseNew::UpdateFinished(bool update_succeeded) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // The update may have failed due to corrupt storage (for instance,
   // an excessive number of invalid add_chunks and sub_chunks).
   // Double-check that the databases are valid.
   // TODO(shess): Providing a checksum for the add_chunk and sub_chunk
   // sections would allow throwing a corruption error in
   // UpdateStarted().
   if (!update_succeeded) {
     if (!browse_store_->CheckValidity())
       DLOG(ERROR) << "Safe-browsing browse database corrupt.";
@@ skipping 111 matching lines @@
         unwanted_software_store_.get(), PrefixSetId::UNWANTED_SOFTWARE,
         FAILURE_UNWANTED_SOFTWARE_DATABASE_UPDATE_FINISH,
         FAILURE_UNWANTED_SOFTWARE_PREFIX_SET_WRITE, true);
   }
 }
 
 void SafeBrowsingDatabaseNew::UpdateWhitelistStore(
     const base::FilePath& store_filename,
     SafeBrowsingStore* store,
     SBWhitelistId whitelist_id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   if (!store)
     return;
 
   // Note: |builder| will not be empty.  The current data store implementation
   // stores all full-length hashes as both full and prefix hashes.
   PrefixSetBuilder builder;
   std::vector<SBAddFullHash> full_hashes;
   if (!store->FinishUpdate(&builder, &full_hashes)) {
     RecordFailure(FAILURE_WHITELIST_DATABASE_UPDATE_FINISH);
     state_manager_.BeginWriteTransaction()->WhitelistEverything(whitelist_id);
     return;
   }
 
   RecordFileSizeHistogram(store_filename);
 
 #if defined(OS_MACOSX)
   base::mac::SetFileBackupExclusion(store_filename);
 #endif
 
   LoadWhitelist(full_hashes, whitelist_id);
 }
 
 void SafeBrowsingDatabaseNew::UpdateHashPrefixStore(
     const base::FilePath& store_filename,
     SafeBrowsingStore* store,
     FailureType failure_type) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // These results are not used after this call. Simply ignore the
   // returned value after FinishUpdate(...).
   PrefixSetBuilder builder;
   std::vector<SBAddFullHash> add_full_hashes_result;
 
   if (!store->FinishUpdate(&builder, &add_full_hashes_result))
     RecordFailure(failure_type);
 
   RecordFileSizeHistogram(store_filename);
 
 #if defined(OS_MACOSX)
   base::mac::SetFileBackupExclusion(store_filename);
 #endif
 }
 
 void SafeBrowsingDatabaseNew::UpdatePrefixSetUrlStore(
     const base::FilePath& db_filename,
     SafeBrowsingStore* url_store,
     PrefixSetId prefix_set_id,
     FailureType finish_failure_type,
     FailureType write_failure_type,
     bool store_full_hashes_in_prefix_set) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(url_store);
 
   // Measure the amount of IO during the filter build.
   base::IoCounters io_before, io_after;
   base::ProcessHandle handle = base::GetCurrentProcessHandle();
   scoped_ptr<base::ProcessMetrics> metric(
 #if !defined(OS_MACOSX)
       base::ProcessMetrics::CreateProcessMetrics(handle)
 #else
       // Getting stats only for the current process is enough, so NULL is fine.
@@ skipping 59 matching lines @@
   }
 
   RecordFileSizeHistogram(db_filename);
 
 #if defined(OS_MACOSX)
   base::mac::SetFileBackupExclusion(db_filename);
 #endif
 }
 
 void SafeBrowsingDatabaseNew::UpdateIpBlacklistStore() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // Note: prefixes will not be empty.  The current data store implementation
   // stores all full-length hashes as both full and prefix hashes.
   PrefixSetBuilder builder;
   std::vector<SBAddFullHash> full_hashes;
   if (!ip_blacklist_store_->FinishUpdate(&builder, &full_hashes)) {
     RecordFailure(FAILURE_IP_BLACKLIST_UPDATE_FINISH);
     LoadIpBlacklist(std::vector<SBAddFullHash>());  // Clear the list.
     return;
   }
 
   const base::FilePath ip_blacklist_filename =
       IpBlacklistDBFilename(db_state_manager_.filename_base());
 
   RecordFileSizeHistogram(ip_blacklist_filename);
 
 #if defined(OS_MACOSX)
   base::mac::SetFileBackupExclusion(ip_blacklist_filename);
 #endif
 
   LoadIpBlacklist(full_hashes);
 }
 
 void SafeBrowsingDatabaseNew::HandleCorruptDatabase() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // Reset the database after the current task has unwound (but only
   // reset once within the scope of a given task).
   if (!reset_factory_.HasWeakPtrs()) {
     RecordFailure(FAILURE_DATABASE_CORRUPT);
-    base::MessageLoop::current()->PostTask(FROM_HERE,
-        base::Bind(&SafeBrowsingDatabaseNew::OnHandleCorruptDatabase,
-                   reset_factory_.GetWeakPtr()));
+    db_task_runner_->PostTask(
+        FROM_HERE, base::Bind(&SafeBrowsingDatabaseNew::OnHandleCorruptDatabase,
+                              reset_factory_.GetWeakPtr()));
   }
 }
 
 void SafeBrowsingDatabaseNew::OnHandleCorruptDatabase() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   RecordFailure(FAILURE_DATABASE_CORRUPT_HANDLER);
   db_state_manager_.set_corruption_detected();  // Stop updating the database.
   ResetDatabase();
 
   // NOTE(shess): ResetDatabase() should remove the corruption, so this should
   // only happen once.  If you are here because you are hitting this after a
   // restart, then I would be very interested in working with you to figure out
   // what is happening, since it may affect real users.
   DLOG(FATAL) << "SafeBrowsing database was corrupt and reset";
 }
 
 // TODO(shess): I'm not clear why this code doesn't have any
 // real error-handling.
 void SafeBrowsingDatabaseNew::LoadPrefixSet(const base::FilePath& db_filename,
                                             WriteTransaction* txn,
                                             PrefixSetId prefix_set_id,
                                             FailureType read_failure_type) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(txn);
   DCHECK(!db_state_manager_.filename_base().empty());
 
   // Only use the prefix set if database is present and non-empty.
   if (!GetFileSizeOrZero(db_filename))
     return;
 
   // Cleanup any stale bloom filter (no longer used).
   // TODO(shess): Track existence to drive removal of this code?
   const base::FilePath bloom_filter_filename =
       BloomFilterForFilename(db_filename);
   base::DeleteFile(bloom_filter_filename, false);
 
   const base::TimeTicks before = base::TimeTicks::Now();
   scoped_ptr<const PrefixSet> new_prefix_set =
       PrefixSet::LoadFile(PrefixSetForFilename(db_filename));
   if (!new_prefix_set.get())
     RecordFailure(read_failure_type);
   txn->SwapPrefixSet(prefix_set_id, new_prefix_set.Pass());
   UMA_HISTOGRAM_TIMES("SB2.PrefixSetLoad", base::TimeTicks::Now() - before);
 }
 
 bool SafeBrowsingDatabaseNew::Delete() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
   DCHECK(!db_state_manager_.filename_base().empty());
 
   // TODO(shess): This is a mess.  SafeBrowsingFileStore::Delete() closes the
   // store before calling DeleteStore().  DeleteStore() deletes transient files
   // in addition to the main file.  Probably all of these should be converted to
   // a helper which calls Delete() if the store exists, else DeleteStore() on
   // the generated filename.
 
   // TODO(shess): Determine if the histograms are useful in any way.  I cannot
   // recall any action taken as a result of their values, in which case it might
@@ skipping 68 matching lines @@
   if (!r12)
     RecordFailure(FAILURE_UNWANTED_SOFTWARE_PREFIX_SET_DELETE);
 
   return r1 && r2 && r3 && r4 && r5 && r6 && r7 && r8 && r9 && r10 && r11 &&
          r12;
 }
 
 void SafeBrowsingDatabaseNew::WritePrefixSet(const base::FilePath& db_filename,
                                              PrefixSetId prefix_set_id,
                                              FailureType write_failure_type) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   // Do not grab the lock to avoid contention while writing to disk. This is
   // safe as only this thread can ever modify |state_manager_|'s prefix sets
   // anyways.

[gab, 2015/02/23 19:53:33]

This comment (and use-case) below is still correct, but should be updated to
refer to the task runner rather than "thread".

[Alexei Svitkine (slow), 2015/02/24 18:08:57]

Done. Also updated the method name that said OnMainThread() to
OnMainTaskRunner() and corresponding enum.

   scoped_ptr<ReadTransaction> txn =
       state_manager_.BeginReadTransactionNoLockOnMainThread();
   const PrefixSet* prefix_set = txn->GetPrefixSet(prefix_set_id);
 
   if (!prefix_set)
     return;
 
   const base::FilePath prefix_set_filename = PrefixSetForFilename(db_filename);
 
   const base::TimeTicks before = base::TimeTicks::Now();
   const bool write_ok = prefix_set->WriteFile(prefix_set_filename);
   UMA_HISTOGRAM_TIMES("SB2.PrefixSetWrite", base::TimeTicks::Now() - before);
 
   RecordFileSizeHistogram(prefix_set_filename);
 
   if (!write_ok)
     RecordFailure(write_failure_type);
 
 #if defined(OS_MACOSX)
   base::mac::SetFileBackupExclusion(prefix_set_filename);
 #endif
 }
 
 void SafeBrowsingDatabaseNew::LoadWhitelist(
     const std::vector<SBAddFullHash>& full_hashes,
     SBWhitelistId whitelist_id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   if (full_hashes.size() > kMaxWhitelistSize) {
     state_manager_.BeginWriteTransaction()->WhitelistEverything(whitelist_id);
     return;
   }
 
   std::vector<SBFullHash> new_whitelist;
   new_whitelist.reserve(full_hashes.size());
   for (std::vector<SBAddFullHash>::const_iterator it = full_hashes.begin();
        it != full_hashes.end(); ++it) {
     new_whitelist.push_back(it->full_hash);
   }
   std::sort(new_whitelist.begin(), new_whitelist.end(), SBFullHashLess);
 
   SBFullHash kill_switch = SBFullHashForString(kWhitelistKillSwitchUrl);
   if (std::binary_search(new_whitelist.begin(), new_whitelist.end(),
                          kill_switch, SBFullHashLess)) {
     // The kill switch is whitelisted hence we whitelist all URLs.
     state_manager_.BeginWriteTransaction()->WhitelistEverything(whitelist_id);
   } else {
     state_manager_.BeginWriteTransaction()->SwapSBWhitelist(whitelist_id,
                                                             &new_whitelist);
   }
 }
 
 void SafeBrowsingDatabaseNew::LoadIpBlacklist(
     const std::vector<SBAddFullHash>& full_hashes) {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(db_task_runner_->RunsTasksOnCurrentThread());
 
   IPBlacklist new_blacklist;
   for (std::vector<SBAddFullHash>::const_iterator it = full_hashes.begin();
        it != full_hashes.end();
        ++it) {
     const char* full_hash = it->full_hash.full_hash;
     DCHECK_EQ(crypto::kSHA256Length, arraysize(it->full_hash.full_hash));
     // The format of the IP blacklist is:
     // SHA-1(IPv6 prefix) + uint8(prefix size) + 11 unused bytes.
     std::string hashed_ip_prefix(full_hash, base::kSHA1Length);
@@ skipping 85 matching lines @@
   else
     NOTREACHED();  // Add support for new lists above.
 
   // Histogram properties as in UMA_HISTOGRAM_COUNTS macro.
   base::HistogramBase* histogram_pointer = base::Histogram::FactoryGet(
       histogram_name, 1, 1000000, 50,
       base::HistogramBase::kUmaTargetedHistogramFlag);
 
   histogram_pointer->Add(file_size_kilobytes);
 }