sandbox/win: Fix warnings found by clang chromium-style plugin on Windows.

sandbox/win/src/handle_closer.cc

Index: sandbox/win/src/handle_closer.cc
diff --git a/sandbox/win/src/handle_closer.cc b/sandbox/win/src/handle_closer.cc
index 4111623038f8310e8fe89e6fb2cfbfcd0ee1df35..2e3a78223bcf33ac6f286e621e0b97873fa72023 100644
--- a/sandbox/win/src/handle_closer.cc
+++ b/sandbox/win/src/handle_closer.cc
@@ -32,7 +32,11 @@ namespace sandbox {
 // Memory buffer mapped from the parent, with the list of handles.
 SANDBOX_INTERCEPT HandleCloserInfo* g_handles_to_close;
 
-HandleCloser::HandleCloser() {}
+HandleCloser::HandleCloser() {
+}
+
+HandleCloser::~HandleCloser() {
+}
 
 ResultCode HandleCloser::AddHandle(const base::char16* handle_type,
                                    const base::char16* handle_name) {