[Sync] Creating sync_sessions component, moving revisit logic.

components/sync_driver/revisit/page_equality.h

-// 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.
-
-#ifndef COMPONENTS_SYNC_DRIVER_PAGE_EQUALITY_H_
-#define COMPONENTS_SYNC_DRIVER_PAGE_EQUALITY_H_
-
-namespace sync_driver {
-
-// An extremely simplistic approach to determining page equality, given two
-// URLs. Some of the notable examples this fails to accommodate are varying
-// schemes, mobile subdomains, unimpactful query parameters/fragments, and
-// page changing headers/cookies.
-class PageEquality {
- public:
-  explicit PageEquality(const GURL& url) : url_(url) {}
-  PageEquality(const PageEquality&) = default;
-  bool IsSamePage(const GURL& url) const { return url == url_; }
-
- private:
-  const GURL url_;
-};
-
-}  // namespace sync_driver
-
-#endif  // COMPONENTS_SYNC_DRIVER_PAGE_EQUALITY_H_