PVer4: Test checksum on startup outside the hotpath of DB load

components/safe_browsing_db/v4_database.h

Index: components/safe_browsing_db/v4_database.h
diff --git a/components/safe_browsing_db/v4_database.h b/components/safe_browsing_db/v4_database.h
index bddba598850d4b5750b1274981242f1112a5a1be..9c2e40541efb72fb0f25c5265c4eb43562717200 100644
--- a/components/safe_browsing_db/v4_database.h
+++ b/components/safe_browsing_db/v4_database.h
@@ -17,9 +17,17 @@ namespace safe_browsing {
 
 class V4Database;
 
+// Scheduled when the database has been read from disk and is ready to process
+// resource reputation requests.
 typedef base::Callback<void(std::unique_ptr<V4Database>)>
     NewDatabaseReadyCallback;
 
+// Scheduled when the checksum for all the stores in the database has been
+// verified to match the expected value. Stores for which the checksum did not
+// match are passed as the argument and need to be reset.
+typedef base::Callback<void(const std::vector<ListIdentifier>&)>
+    DatabaseReadyForUpdatesCallback;
+
 // This callback is scheduled once the database has finished processing the
 // update requests for all stores and is ready to process the next set of update
 // requests.
@@ -116,8 +124,17 @@ class V4Database {
       const StoresToCheck& stores_to_check,
       StoreAndHashPrefixes* matched_store_and_full_hashes);
 
-  // Deletes the current database and creates a new one.
-  virtual bool ResetDatabase();
+  // Resets the stores in |stores_to_reset| to an empty state. This is done if
+  // the checksum doesn't match the expected value.
+  void ResetStores(const std::vector<ListIdentifier>& stores_to_reset);
+
+  // Schedules verification of the checksum of each store read from disk on task
+  // runner. If the checksum doesn't match, that store is passed to the
+  // |db_ready_for_updates_callback|. At the end,
+  // |db_ready_for_updates_callback| is scheduled (on the same thread as it was
+  // called) to indicate that the database updates can now be scheduled.
+  void VerifyChecksum(
+      DatabaseReadyForUpdatesCallback db_ready_for_updates_callback);
 
  protected:
   V4Database(const scoped_refptr<base::SequencedTaskRunner>& db_task_runner,
@@ -155,6 +172,11 @@ class V4Database {
   void UpdatedStoreReady(ListIdentifier identifier,
                          std::unique_ptr<V4Store> store);
 
+  // See |VerifyChecksum|.
+  void VerifyChecksumOnTaskRunner(
+      const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
+      DatabaseReadyForUpdatesCallback db_ready_for_updates_callback);
+
   const scoped_refptr<base::SequencedTaskRunner> db_task_runner_;
 
   // Map of ListIdentifier to the V4Store.