[ios] Adds code to support the iOS Handoff feature.

components/handoff/pref_names_ios.h

Index: components/handoff/pref_names_ios.h
diff --git a/components/handoff/pref_names_ios.h b/components/handoff/pref_names_ios.h
new file mode 100644
index 0000000000000000000000000000000000000000..9c585a21da8ee60c241f81b2ec05c55c6110c9df
--- /dev/null
+++ b/components/handoff/pref_names_ios.h
@@ -0,0 +1,14 @@
+// Copyright 2016 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.
+
+#ifndef COMPONENTS_HANDOFF_PREF_NAMES_IOS_H_
+#define COMPONENTS_HANDOFF_PREF_NAMES_IOS_H_
+
+namespace prefs {
+
+extern const char kIosHandoffToOtherDevices[];
+
+}  // namespace prefs
+
+#endif  // COMPONENTS_HANDOFF_PREF_NAMES_IOS_H_