[ios] Adds test provider implementations.

ios/public/provider/chrome/browser/sessions/test_synced_window_delegates_getter.cc

Index: ios/public/provider/chrome/browser/sessions/test_synced_window_delegates_getter.cc
diff --git a/ios/public/provider/chrome/browser/sessions/test_synced_window_delegates_getter.cc b/ios/public/provider/chrome/browser/sessions/test_synced_window_delegates_getter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8375f3bc43b9e41630873f70cdd361e39f35fb54
--- /dev/null
+++ b/ios/public/provider/chrome/browser/sessions/test_synced_window_delegates_getter.cc
@@ -0,0 +1,15 @@
+// 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.
+
+#include "ios/public/provider/chrome/browser/sessions/test_synced_window_delegates_getter.h"
+
+std::set<const sync_sessions::SyncedWindowDelegate*>
+TestSyncedWindowDelegatesGetter::GetSyncedWindowDelegates() {
+  return std::set<const sync_sessions::SyncedWindowDelegate*>();
+}
+
+const sync_sessions::SyncedWindowDelegate*
+TestSyncedWindowDelegatesGetter::FindById(SessionID::id_type id) {
+  return nullptr;
+}