libweave: Port base/ changes from Chromium project

Now this makes the state of base/ match libchrome's implementation
on Brillo and Chrome OS.

Change-Id: I1c1eb30d2669aeb58a77f332f8c69f130d00878c
Reviewed-on: https://weave-review.googlesource.com/3065
Reviewed-by: Robert Ginda <rginda@google.com>
diff --git a/third_party/chromium/base/logging.cc b/third_party/chromium/base/logging.cc
index 6306f47..ab97073 100644
--- a/third_party/chromium/base/logging.cc
+++ b/third_party/chromium/base/logging.cc
@@ -233,7 +233,7 @@
 }
 
 void RawLog(int level, const char* message) {
-  if (level >= g_min_log_level) {
+  if (level >= g_min_log_level && message) {
     size_t bytes_written = 0;
     const size_t message_len = strlen(message);
     int rv;