SafeBrowising: Read and write V4Store from/to disk

components/safe_browsing_db/v4_database.cc

Index: components/safe_browsing_db/v4_database.cc
diff --git a/components/safe_browsing_db/v4_database.cc b/components/safe_browsing_db/v4_database.cc
index 0b5acf79d967421995c06e4cbe0092a5a334c1ed..5c80fecb0d68cbb36a10250dcfa7bce82cc0d219 100644
--- a/components/safe_browsing_db/v4_database.cc
+++ b/components/safe_browsing_db/v4_database.cc
@@ -6,6 +6,7 @@
 
 #include "base/callback.h"
 #include "base/debug/leak_annotations.h"
+#include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "components/safe_browsing_db/v4_database.h"
@@ -54,6 +55,10 @@ void V4Database::CreateOnTaskRunner(
     ANNOTATE_LEAKING_OBJECT_PTR(factory_);
   }
 
+  if (!base::CreateDirectory(base_path)) {
+    NOTREACHED();
+  }
+
   std::unique_ptr<StoreMap> store_map = base::MakeUnique<StoreMap>();
   for (const auto& store_info : store_file_name_map) {
     const UpdateListIdentifier& update_list_identifier = store_info.first;