Fix a c_str() use-after-free bug in the printing code.

printing/printing_context_win.cc

Index: printing/printing_context_win.cc
diff --git a/printing/printing_context_win.cc b/printing/printing_context_win.cc
index a94c71fffac7568cdf355f24562b9bd275ee5df3..d0d7a1cfb7baa79eee71357be7216b0da8e9e67c 100644
--- a/printing/printing_context_win.cc
+++ b/printing/printing_context_win.cc
@@ -262,7 +262,8 @@ PrintingContext::Result PrintingContext::NewDocument(
     return OnError();
 
   DOCINFO di = { sizeof(DOCINFO) };
-  di.lpszDocName = UTF16ToWide(document_name).c_str();
+  const std::wstring& document_name_wide = UTF16ToWide(document_name);
+  di.lpszDocName = document_name_wide.c_str();
 
   // Is there a debug dump directory specified? If so, force to print to a file.
   FilePath debug_dump_path = PrintedDocument::debug_dump_path();