Implement InstanceID API functions.

chrome/test/data/extensions/api_test/instance_id/get_id/get_id.js

Index: chrome/test/data/extensions/api_test/instance_id/get_id/get_id.js
diff --git a/chrome/test/data/extensions/api_test/instance_id/get_id/get_id.js b/chrome/test/data/extensions/api_test/instance_id/get_id/get_id.js
new file mode 100644
index 0000000000000000000000000000000000000000..53bd36fd314e901ce09939e513335643887ed3c2
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/instance_id/get_id/get_id.js
@@ -0,0 +1,53 @@
+// 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.
+
+function getIDWithoutCallback() {
+  try {
+    chrome.instanceID.getID();
+    chrome.test.fail("Calling getID without callback should fail.");
+  } catch (e) {
+    chrome.test.succeed();
+  };
+}
+
+function getIDWithCallback() {
+  chrome.instanceID.getID(function(id) {
+    if (chrome.runtime.lastError) {
+      chrome.test.fail(
+          "chrome.runtime.lastError: " + chrome.runtime.lastError.message);
+      return;
+    }
+    if (id == "") {
+      chrome.test.fail("Empty ID returned.");
+      return;
+    }
+
+    chrome.test.succeed();
+  });
+}
+
+var oldID;
+function getIDTwice() {
+  chrome.instanceID.getID(function(id) {
+    if (!id) {
+      chrome.test.fail("ID should not be zero.");
+      return;
+    }
+    oldID = id;
+
+    chrome.instanceID.getID(function(id) {
+        if (!id || id != oldID) {
+          chrome.test.fail("Same ID should be returned.");
+          return;
+        }
+        chrome.test.succeed();
+      });
+  });
+}
+
+chrome.test.runTests([
+  getIDWithoutCallback,
+  getIDWithCallback,
+  getIDTwice,
+]);