[sync] WebContentsObserver based sessions notifications

components/sync_sessions/synced_tab_delegate.h

 // Copyright (c) 2012 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_SESSIONS_SYNCED_TAB_DELEGATE_H__
 #define COMPONENTS_SYNC_SESSIONS_SYNCED_TAB_DELEGATE_H__
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "components/sessions/core/serialized_navigation_entry.h"
 #include "components/sessions/core/session_id.h"
 #include "ui/base/page_transition_types.h"
 #include "url/gurl.h"
 
 namespace sync_sessions {
 class SyncSessionsClient;
 }
 
 namespace sync_sessions {
 
+enum InvalidTab { kInvalidTabID = -1 };
+
 // A SyncedTabDelegate is used to insulate the sync code from depending
 // directly on WebContents, NavigationController, and the extensions TabHelper.
 class SyncedTabDelegate {
  public:
   virtual ~SyncedTabDelegate();
 
   // Methods from TabContents.
   virtual SessionID::id_type GetWindowId() const = 0;
   virtual SessionID::id_type GetSessionId() const = 0;
   virtual bool IsBeingDestroyed() const = 0;
 
+  // Get the tab id of the tab responsible for opening this tab, if applicable.
+  // Returns kUnknownTabID(-1) if no such tab relationship is known.
+  virtual SessionID::id_type GetSourceTabID() const = 0;
+
   // Method derived from extensions TabHelper.
   virtual std::string GetExtensionAppId() const = 0;
 
   // Methods from NavigationController.
   virtual bool IsInitialBlankNavigation() const = 0;
   virtual int GetCurrentEntryIndex() const = 0;
   virtual int GetEntryCount() const = 0;
   virtual GURL GetVirtualURLAtIndex(int i) const = 0;
   virtual GURL GetFaviconURLAtIndex(int i) const = 0;
   virtual ui::PageTransition GetTransitionAtIndex(int i) const = 0;
@@ skipping 18 matching lines @@
   // tab should be preserved.
   virtual bool IsPlaceholderTab() const = 0;
 
  protected:
   SyncedTabDelegate();
 };
 
 }  // namespace sync_sessions
 
 #endif  // COMPONENTS_SYNC_SESSIONS_SYNCED_TAB_DELEGATE_H__