win sandbox: Fix minor c++ violation, no functionality change

sandbox/src/handle_closer.h

Index: sandbox/src/handle_closer.h
diff --git a/sandbox/src/handle_closer.h b/sandbox/src/handle_closer.h
index 76b1a51d87635e53c1c9fd1685e985cc4b939404..f3b84924b1e1a4743e9028f086ac4812e0f6a37b 100644
--- a/sandbox/src/handle_closer.h
+++ b/sandbox/src/handle_closer.h
@@ -46,8 +46,7 @@ class HandleCloser {
   // Adds a handle that will be closed in the target process after lockdown.
   // A NULL value for handle_name indicates all handles of the specified type.
   // An empty string for handle_name indicates the handle is unnamed.
-  ResultCode HandleCloser::AddHandle(const char16* handle_type,
-                                     const char16* handle_name);
+  ResultCode AddHandle(const char16* handle_type, const char16* handle_name);
 
   // Serializes and copies the closer table into the target process.
   bool InitializeTargetHandles(TargetProcess* target);