Don't evaluate args to LOG(INFO) and LOG(WARNING) in release builds.

base/logging.h

Index: base/logging.h
diff --git a/base/logging.h b/base/logging.h
index a78b7864c9705647fe56884a8a51c7acdf5b2554..e95bd3b5db8eb02c823d1191cbc6299839858b60 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -238,6 +238,9 @@ BASE_EXPORT void SetMinLogLevel(int level);
 // Gets the current log level.
 BASE_EXPORT int GetMinLogLevel();
 
+// Used by LOG_IS_ON to lazy-evaluate stream arguments.
+BASE_EXPORT bool ShouldCreateLogMessage(int severity);
+
 // Gets the VLOG default verbosity level.
 BASE_EXPORT int GetVlogVerbosity();
 
@@ -340,7 +343,7 @@ const LogSeverity LOG_0 = LOG_ERROR;
 // LOG_IS_ON(DFATAL) always holds in debug mode. In particular, CHECK()s will
 // always fire if they fail.
 #define LOG_IS_ON(severity) \
-  ((::logging::LOG_ ## severity) >= ::logging::GetMinLogLevel())
+  (::logging::ShouldCreateLogMessage(::logging::LOG_##severity))
 
 // We can't do any caching tricks with VLOG_IS_ON() like the
 // google-glog version since it requires GCC extensions.  This means