shill: Replace NULL with nullptr.

BUG=None
TEST=`USE=wimax FEATURES=test emerge-$BOARD shill`

Change-Id: I30ab47ff32dcadad09ae7a2baf4d4123a6ef0d8e
Reviewed-on: https://chromium-review.googlesource.com/220657
Reviewed-by: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
diff --git a/service.h b/service.h
index 34f8df8..acbca74 100644
--- a/service.h
+++ b/service.h
@@ -429,7 +429,7 @@
   const ProfileRefPtr &profile() const;
 
   // Sets the profile property of this service. Broadcasts the new value if it's
-  // not NULL. If the new value is NULL, the service will either be set to
+  // not nullptr. If the new value is nullptr, the service will either be set to
   // another profile afterwards or it will not be visible and not monitored
   // anymore.
   void SetProfile(const ProfileRefPtr &p);