Add missing sample that got inlined into the docs.

functions/background/index.js

@@ -37,7 +37,8 @@ exports.helloWorld = function helloWorld (context, data) {
 var request = require('request-promise');
 
 /**
- * Background Cloud Function that returns a Promise.
+ * Background Cloud Function that returns a Promise. Note that we don't pass
+ * a "context" argument to the function.
  *
  * @param {Object} data Request data, provided by a trigger.
  * @returns {Promise}
@@ -48,3 +49,20 @@ exports.helloPromise = function helloPromise (data) {
   });
 };
 // [END helloPromise]
+
+// [START helloSynchronous]
+/**
+ * Background Cloud Function that returns synchronously. Note that we don't pass
+ * a "context" argument to the function.
+ *
+ * @param {Object} data Request data, provided by a trigger.
+ */
+exports.helloSynchronous = function helloSynchronous (data) {
+  // This function returns synchronously
+  if (data.something === true) {
+    return 'Something is true!';
+  } else {
+    throw new Error('Something was not true!');
+  }
+};
+// [END helloSynchronous]

test/functions/background.test.js

@@ -79,6 +79,20 @@ test.cb.serial('should make a promise request', function (t) {
     t.fail();
   });
 });
+test('should return synchronously', function (t) {
+  var backgroundSample = getSample();
+  t.is(backgroundSample.sample.helloSynchronous({
+    something: true
+  }), 'Something is true!');
+});
+test('should throw an error', function (t) {
+  var backgroundSample = getSample();
+  t.throws(function () {
+    backgroundSample.sample.helloSynchronous({
+      something: false
+    })
+  }, Error, 'Something was not true!');
+});
 
 test.after(function () {
   console.error.restore();