Pass error messages from native messaging to web-app.

remoting/host/it2me/it2me_native_messaging_host.cc

Index: remoting/host/it2me/it2me_native_messaging_host.cc
diff --git a/remoting/host/it2me/it2me_native_messaging_host.cc b/remoting/host/it2me/it2me_native_messaging_host.cc
index 1bf175ecda500dbf33a96b693631d76230e145dd..118ccb185ff95b2e4cdf7cda5371cc5ecf079415 100644
--- a/remoting/host/it2me/it2me_native_messaging_host.cc
+++ b/remoting/host/it2me/it2me_native_messaging_host.cc
@@ -115,10 +115,18 @@ void It2MeNativeMessagingHost::OnMessage(const std::string& message) {
 void It2MeNativeMessagingHost::Start(Client* client) {
   DCHECK(task_runner()->BelongsToCurrentThread());
   client_ = client;
+#if !defined(OS_CHROMEOS)
+  // Don't install a log message handler on ChromeOS because we run in the
+  // browser process and don't want to intercept all its log messages.
+  log_message_handler_.reset(
+      new LogMessageHandler(
+          base::Bind(&It2MeNativeMessagingHost::SendMessageToClient,
+                     base::Unretained(this))));
+#endif  // !defined(OS_CHROMEOS)
 }
 
 void It2MeNativeMessagingHost::SendMessageToClient(
-    scoped_ptr<base::DictionaryValue> message) const {
+    scoped_ptr<base::Value> message) const {
   DCHECK(task_runner()->BelongsToCurrentThread());
   std::string message_json;
   base::JSONWriter::Write(*message, &message_json);