Android: Make netlog available in startup traces.

net/log/trace_net_log_observer.cc

Index: net/log/trace_net_log_observer.cc
diff --git a/net/log/trace_net_log_observer.cc b/net/log/trace_net_log_observer.cc
index 4c7b7dcc605be4d7263ab6b59e589443a19fdca5..bae83a5ac141af05e17ad43ee8cd4063687843bd 100644
--- a/net/log/trace_net_log_observer.cc
+++ b/net/log/trace_net_log_observer.cc
@@ -90,6 +90,10 @@ void TraceNetLogObserver::WatchForTraceStart(NetLog* netlog) {
   DCHECK(!net_log_to_watch_);
   DCHECK(!net_log());
   net_log_to_watch_ = netlog;
+  // Tracing can start before the observer is even created, for instance for
+  // startup tracing.
+  if (base::trace_event::TraceLog::GetInstance()->IsEnabled())
+    OnTraceLogEnabled();
   base::trace_event::TraceLog::GetInstance()->AddEnabledStateObserver(this);
 }