storage: Use stl utilities from the base namespace

storage/browser/fileapi/sandbox_file_system_backend_delegate.cc

Index: storage/browser/fileapi/sandbox_file_system_backend_delegate.cc
diff --git a/storage/browser/fileapi/sandbox_file_system_backend_delegate.cc b/storage/browser/fileapi/sandbox_file_system_backend_delegate.cc
index f4714c78b1d6bcec61af05e3ab6eb7535b6ac977..b6b3a627424ecc6d170a3d6aa1d25aaf5054a2f9 100644
--- a/storage/browser/fileapi/sandbox_file_system_backend_delegate.cc
+++ b/storage/browser/fileapi/sandbox_file_system_backend_delegate.cc
@@ -393,7 +393,8 @@ int64_t SandboxFileSystemBackendDelegate::GetOriginUsageOnFileTaskRunner(
 
   // Don't use usage cache and return recalculated usage for sticky invalidated
   // origins.
-  if (ContainsKey(sticky_dirty_origins_, std::make_pair(origin_url, type)))
+  if (base::ContainsKey(sticky_dirty_origins_,
+                        std::make_pair(origin_url, type)))
     return RecalculateUsage(file_system_context, origin_url, type);
 
   base::FilePath base_path =