Add encounteredError() to AssociatedInterfacePtrController.

Indicates whether an error has been encountered by the interface endpoint client. If true, method calls made on this interface will be dropped (and may already have been dropped).

BUG=695635

Review-Url: https://codereview.chromium.org/2840333002
Cr-Commit-Position: refs/heads/master@{#467869}

mojo/public/js/associated_bindings.js

@@ -116,6 +116,13 @@ define("mojo/public/js/associated_bindings", [
     this.reset();
   };
 
+  // Indicates whether an error has been encountered. If true, method calls
+  // on this interface will be dropped (and may already have been dropped).
+  AssociatedInterfacePtrController.prototype.getEncounteredError = function() {
+    return this.interfaceEndpointClient_ ?
+        this.interfaceEndpointClient_.getEncounteredError() : false;
+  };
+
   AssociatedInterfacePtrController.prototype.setConnectionErrorHandler =
       function(callback) {
     if (!this.isBound()) {

mojo/public/js/lib/interface_endpoint_client.js

@@ -232,6 +232,10 @@ define("mojo/public/js/lib/interface_endpoint_client", [
     this.controlMessageProxy_.requireVersion(version);
   };
 
+  InterfaceEndpointClient.prototype.getEncounteredError = function() {
+    return this.encounteredError_;
+  };
+
   var exports = {};
   exports.InterfaceEndpointClient = InterfaceEndpointClient;