Add new certificateProvider extension API.

chrome/renderer/resources/extensions/certificate_provider_custom_bindings.js

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var binding = require('binding').Binding.create('certificateProvider');
+var certificateProviderInternal = require('binding').Binding.create(
+    'certificateProviderInternal').generate();
+var eventBindings = require('event_bindings');
+
+var certificateProviderSchema =
+    requireNative('schema_registry').GetSchema('certificateProvider')
+var utils = require('utils');
+var validate = require('schemaUtils').validate;
+
+// Custom bindings for chrome.certificateProvider API.
+// The bindings are used to implement callbacks for the API events. Internally
+// each event is passed a requestId argument used to identify the callback
+// associated with the event. This argument is massaged out from the event
+// arguments before dispatching the event to consumers. A callback is appended
+// to the event arguments. The callback wraps an appropriate
+// chrome.certificateProviderInternal API function that is used to report the
+// event result from the extension. The function is passed the requestId and
+// values provided by the extension. It validates that the values provided by
+// the extension match chrome.certificateProvider event callback schemas. It
+// also ensures that a callback is run at most once. In case there is an
+// exception during event dispatching, the chrome.certificateProviderInternal
+// function is called with a default error value.
+
+// Handles a chrome.certificateProvider event as described in the file comment.
+// |eventName|: The event name. The first argument of the event must be a
+//     request id.
+// |internalReportFunc|: The function that should be called to report results in
+//     reply to an event. The first argument of the function must be the request
+//     id that was received with the event.
+function handleEvent(eventName, internalReportFunc) {
+  var eventSchema =
+      utils.lookup(certificateProviderSchema.events, 'name', eventName);
+  var callbackSchema = utils.lookup(eventSchema.parameters, 'type', 'function');
+
+  eventBindings.registerArgumentMassager(
+      'certificateProvider.' + eventName,
+      function(args, dispatch) {
+        var responded = false;
+
+        // Function provided to the extension as the event callback argument.
+        // The extension calls this to report results in reply to the event.
+        // It throws an exception if called more than once and if the provided
+        // results don't match the callback schema.
+        var reportFunc = function(reportArg1, reportArg2) {
+          if (responded) {
+            throw new Error(
+                'Event callback must not be called more than once.');
+          }
+
+          var reportArgs = [reportArg1];
+          if (reportArg2 !== undefined)
+            reportArgs.push(reportArg2);
+          var finalArgs = [];
+          try {
+            // Validates that the results reported by the extension matche the
+            // callback schema of the event. Throws an exception in case of an
+            // error.
+            validate(reportArgs, callbackSchema.parameters);
+            finalArgs = reportArgs;
+          } finally {
+            responded = true;
+            internalReportFunc.apply(
+                null, [args[0] /* requestId */].concat(finalArgs));
+          }
+        };
+        dispatch(args.slice(1).concat(reportFunc));
+      });
+}
+
+handleEvent('onCertificatesRequested',
+            certificateProviderInternal.reportCertificates);
+
+handleEvent('onSignDigestRequested',
+            certificateProviderInternal.reportSignature);
+
+exports.binding = binding.generate();