Add new extension APIs related to animation policy.

chrome/browser/accessibility/animation_policy_prefs.cc

+// 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.
+
+#include "chrome/browser/accessibility/animation_policy_prefs.h"
+
+#include "chrome/common/pref_names.h"
+#include "components/pref_registry/pref_registry_syncable.h"
+
+const char kAnimationPolicyAllowed[] = "allowed";
+const char kAnimationPolicyOnce[] = "once";
+const char kAnimationPolicyNone[] = "none";
+
+void RegisterAnimationPolicyPrefs(user_prefs::PrefRegistrySyncable* registry) {
+  registry->RegisterStringPref(
+      prefs::kAnimationPolicy,
+      kAnimationPolicyAllowed,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+}