Enforce WARN_UNUSED_RESULT attribute on Windows

chrome/service/cloud_print/print_system_win.cc

Index: chrome/service/cloud_print/print_system_win.cc
diff --git a/chrome/service/cloud_print/print_system_win.cc b/chrome/service/cloud_print/print_system_win.cc
index 26c5626373bd17e3f580838d4f89a649124602da..02016cf76978e202ffd9565b08541e156a3e9fd1 100644
--- a/chrome/service/cloud_print/print_system_win.cc
+++ b/chrome/service/cloud_print/print_system_win.cc
@@ -7,6 +7,7 @@
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/json/json_writer.h"
+#include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/thread_task_runner_handle.h"
@@ -435,7 +436,7 @@ class JobSpoolerWin : public PrintSystem::JobSpooler {
               pdf_path,
               printing::PdfRenderSettings(render_area, render_dpi, false))) {
         // The object will self-destruct when the child process dies.
-        utility_host.release();
+        ignore_result(utility_host.release());
       } else {
         client_task_runner->PostTask(
             FROM_HERE, base::Bind(&Core::PrintJobDone, this, false));
@@ -575,7 +576,7 @@ class PrinterCapsHandler : public ServiceUtilityProcessHost::Client {
         new ServiceUtilityProcessHost(this, client_task_runner.get()));
     if (utility_host->StartGetPrinterCapsAndDefaults(printer_name_)) {
       // The object will self-destruct when the child process dies.
-      utility_host.release();
+      ignore_result(utility_host.release());
     } else {
       client_task_runner->PostTask(
           FROM_HERE, base::Bind(&PrinterCapsHandler::OnChildDied, this));
@@ -589,7 +590,7 @@ class PrinterCapsHandler : public ServiceUtilityProcessHost::Client {
         new ServiceUtilityProcessHost(this, client_task_runner.get()));
     if (utility_host->StartGetPrinterSemanticCapsAndDefaults(printer_name_)) {
       // The object will self-destruct when the child process dies.
-      utility_host.release();
+      ignore_result(utility_host.release());
     } else {
       client_task_runner->PostTask(
           FROM_HERE, base::Bind(&PrinterCapsHandler::OnChildDied, this));