Move session_id.{cc,h} from chrome/browser/sessions to components/sessions

chrome/browser/sessions/session_tab_helper.h

 // Copyright (c) 2011 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 CHROME_BROWSER_SESSIONS_SESSION_TAB_HELPER_H_
 #define CHROME_BROWSER_SESSIONS_SESSION_TAB_HELPER_H_
 
 #include "base/basictypes.h"
-#include "chrome/browser/sessions/session_id.h"
+#include "components/sessions/session_id.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 // This class keeps the extension API's windowID up-to-date with the current
 // window of the tab.
 class SessionTabHelper : public content::WebContentsObserver,
                          public content::WebContentsUserData<SessionTabHelper> {
  public:
   virtual ~SessionTabHelper();
 
   // Returns the identifier used by session restore for this tab.
   const SessionID& session_id() const { return session_id_; }
 
   // Identifier of the window the tab is in.
   void SetWindowID(const SessionID& id);
   const SessionID& window_id() const { return window_id_; }
 
+  // If the specified WebContents has a SessionTabHelper (probably because it
+  // was used as the contents of a tab), returns a tab id. This value is
+  // immutable for a given tab. It will be unique across Chrome within the
+  // current session, but may be re-used across sessions. Returns -1
+  // for a NULL WebContents or if the WebContents has no SessionTabHelper.
+  static SessionID::id_type IdForTab(const content::WebContents* tab);
+
+  // If the specified WebContents has a SessionTabHelper (probably because it
+  // was used as the contents of a tab), and has ever been attached to a Browser
+  // window, returns Browser::session_id().id() for that Browser. If the tab is
+  // being dragged between Browser windows, returns the old window's id value.
+  // If the WebContents has a SessionTabHelper but has never been attached to a
+  // Browser window, returns an id value that is different from that of any
+  // Browser. Returns -1 for a NULL WebContents or if the WebContents has no
+  // SessionTabHelper.
+  static SessionID::id_type IdForWindowContainingTab(
+      const content::WebContents* tab);
+
   // content::WebContentsObserver:
   virtual void RenderViewCreated(
       content::RenderViewHost* render_view_host) OVERRIDE;
   virtual void UserAgentOverrideSet(const std::string& user_agent) OVERRIDE;
 
  private:
   explicit SessionTabHelper(content::WebContents* contents);
   friend class content::WebContentsUserData<SessionTabHelper>;
 
   // Unique identifier of the tab for session restore. This id is only unique
   // within the current session, and is not guaranteed to be unique across
   // sessions.
   const SessionID session_id_;
 
   // Unique identifier of the window the tab is in.
   SessionID window_id_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionTabHelper);
 };
 
 #endif  // CHROME_BROWSER_SESSIONS_SESSION_TAB_HELPER_H_