Add an explicit bool conversion to scoped_refptr<T>.

chrome/installer/util/wmi.cc

Index: chrome/installer/util/wmi.cc
diff --git a/chrome/installer/util/wmi.cc b/chrome/installer/util/wmi.cc
index 20c1050600f8c6c5f9f64ed862a755d89e47a06d..2f79e43fe90d7cc3d4788c4a520e377d29a1f552 100644
--- a/chrome/installer/util/wmi.cc
+++ b/chrome/installer/util/wmi.cc
@@ -69,7 +69,7 @@ bool WMI::CreateClassMethodObject(IWbemServices* wmi_services,
   if (FAILED(hr))
     return false;
 
-  if (NULL == params_def) {
+  if (!params_def) {
     // You hit this special case if the WMI class is not a CIM class. MSDN
     // sometimes tells you this. Welcome to WMI hell.
     return false;