Replace ASSERT by RTC_DCHECK in all non-test code.

webrtc/base/networkmonitor.cc

Index: webrtc/base/networkmonitor.cc
diff --git a/webrtc/base/networkmonitor.cc b/webrtc/base/networkmonitor.cc
index 12076bd24e33ccdc189b876becf94ad02303b486..ddba348a73455114a5a9d4de43a20d0d2f217b9c 100644
--- a/webrtc/base/networkmonitor.cc
+++ b/webrtc/base/networkmonitor.cc
@@ -10,6 +10,7 @@
 
 #include "webrtc/base/networkmonitor.h"
 
+#include "webrtc/base/checks.h"
 #include "webrtc/base/common.h"
 
 namespace {
@@ -35,7 +36,7 @@ void NetworkMonitorBase::OnNetworksChanged() {
 }
 
 void NetworkMonitorBase::OnMessage(Message* msg) {
-  ASSERT(msg->message_id == UPDATE_NETWORKS_MESSAGE);
+  RTC_DCHECK(msg->message_id == UPDATE_NETWORKS_MESSAGE);
   SignalNetworksChanged();
 }