Expose privacy-relevant preferences via Chrome's extension API.

chrome/test/data/extensions/api_test/preference/standard/test.html

+<script>
+// Preferences API test
+// Run with browser_tests --gtest_filter=ExtensionApiTest.PreferenceApi
+
+var preferences_to_test = [
+  {
+    root: chrome.experimental.privacy.network,
+    preferences: [
+      'networkPredictionEnabled'
+    ]
+  },
+  {
+    root: chrome.experimental.privacy.websites,
+    preferences: [
+      'thirdPartyCookiesAllowed',
+      'hyperlinkAuditingEnabled',
+      'referrersEnabled'
+    ]
+  },
+  {
+    root: chrome.experimental.privacy.services,
+    preferences: [
+      'alternateErrorPagesEnabled',
+      'autofillEnabled',
+      'instantEnabled',
+      // TODO(mkwst): 'metricsReportingEnabled',
+      'safeBrowsingEnabled',
+      'searchSuggestEnabled',
+      'translationServiceEnabled'
+    ]
+  },
+];
+
+function expect(expected, message) {
+  return chrome.test.callbackPass(function(value) {
+    chrome.test.assertEq(expected, value, message);
+  });
+}
+
+function expectFalse(pref) {
+  return expect({
+    value: false,
+    levelOfControl: 'controllable_by_this_extension'
+  }, '`' + pref + '` is expected to be false.');
+}
+
+function prefGetter(pref) {
+  this[pref].get({}, expectFalse(pref));
+}
+
+function prefSetter(pref) {
+  this[pref].set({value: true}, chrome.test.callbackPass());
+}
+
+chrome.test.runTests([
+  function getPreferences() {
+    for (var i = 0; i < preferences_to_test.length; i++) {
+      preferences_to_test[i].preferences.forEach(
+          prefGetter.bind(preferences_to_test[i].root));
+    }
+  },
+  function setGlobals() {
+    for (var i = 0; i < preferences_to_test.length; i++) {
+      preferences_to_test[i].preferences.forEach(
+          prefSetter.bind(preferences_to_test[i].root));
+    }
+  }
+]);
+</script>