Pass error messages from native messaging to web-app.

remoting/webapp/crd/js/host_daemon_facade.js

Index: remoting/webapp/crd/js/host_daemon_facade.js
diff --git a/remoting/webapp/crd/js/host_daemon_facade.js b/remoting/webapp/crd/js/host_daemon_facade.js
index 544abd39683d617c787e344caa5695f963b32a6a..cea917212dc8d0f342fc395b8d0a7b7b0260cf87 100644
--- a/remoting/webapp/crd/js/host_daemon_facade.js
+++ b/remoting/webapp/crd/js/host_daemon_facade.js
@@ -196,7 +196,13 @@ remoting.HostDaemonFacade.prototype.onIncomingMessage_ = function(message) {
   try {
     var type = base.getStringAttr(message, 'type');
     if (type != reply.type) {
-      throw 'Expected reply type: ' + reply.type + ', got: ' + type;
+      throw new Error('Expected reply type: ' + reply.type + ', got: ' + type);
+    }
+    var error_message = base.getStringAttr(message, 'error_message', '');
+    if (error_message) {
+      var error_location = base.getStringAttr(message, 'error_location',
+                                              '<unknown>')
+      console.error(error_message + ' at ' + error_location);
     }
     reply.deferred.resolve(message);

[Sergey Ulanov, 2015/08/06 22:40:57]

should we call reject() in case there was an error?

[Jamie, 2015/08/06 23:06:17]

I don't think so. The contract here is that the caller requests that a message
be sent and the Promise is fulfilled when the reply arrives, whether it be
success or failure. This code should ideally be generic and not attempt any
parsing of the message at all (TBH, I'm not convinced that this is the right
place to print the error, but the alternative is duplicating it at each
call-site, which seems worse).

   } catch (/** @type {*} */ e) {