Move all core files in //components/sessions into core/ subdir

ios/chrome/browser/sessions/ios_chrome_session_tab_helper.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 IOS_CHROME_BROWSER_SESSIONS_IOS_CHROME_SESSION_TAB_HELPER_H_
 #define IOS_CHROME_BROWSER_SESSIONS_IOS_CHROME_SESSION_TAB_HELPER_H_
 
 #include "base/basictypes.h"
-#include "components/sessions/session_id.h"
+#include "components/sessions/core/session_id.h"
 #include "ios/web/public/web_state/web_state_user_data.h"
 
 class IOSChromeSessionTabHelper
     : public web::WebStateUserData<IOSChromeSessionTabHelper> {
  public:
   ~IOSChromeSessionTabHelper() override;
 
   // Returns the identifier used by session restore for this tab.
   const SessionID& session_id() const { return session_id_; }
 
@@ skipping 10 matching lines @@
   // sessions.
   const SessionID session_id_;
 
   // Unique identifier of the window the tab is in.
   SessionID window_id_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSChromeSessionTabHelper);
 };
 
 #endif  // IOS_CHROME_BROWSER_SESSIONS_IOS_CHROME_SESSION_TAB_HELPER_H_