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 a64ad48d5d0f0e9cea1d40d149c775597aed144e..22533e1f275e46c205eb33535f17036160ea7047 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"
@@ -49,6 +50,10 @@ 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;