[ios] Adds test provider implementations.

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

+// 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 IOS_PUBLIC_PROVIDER_CHROME_BROWSER_SESSIONS_TEST_SYNCED_WINDOW_DELEGATES_GETTER_H_
+#define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_SESSIONS_TEST_SYNCED_WINDOW_DELEGATES_GETTER_H_
+
+#include "base/macros.h"
+#include "components/sync_sessions/synced_window_delegates_getter.h"
+
+class TestSyncedWindowDelegatesGetter
+    : public sync_sessions::SyncedWindowDelegatesGetter {
+ public:
+  TestSyncedWindowDelegatesGetter() {}
+  ~TestSyncedWindowDelegatesGetter() override {}
+
+  // SyncedWindowDelegatesGetter.
+  std::set<const sync_sessions::SyncedWindowDelegate*>
+  GetSyncedWindowDelegates() override;
+  const sync_sessions::SyncedWindowDelegate* FindById(
+      SessionID::id_type id) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestSyncedWindowDelegatesGetter);
+};
+
+#endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_SESSIONS_TEST_SYNCED_WINDOW_DELEGATES_GETTER_H_