Revert of [Sync] Put session tracker in charge of maintaining local state.

components/sync_sessions/sessions_sync_manager.h

 // Copyright 2014 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_SESSIONS_SYNC_MANAGER_H_
 #define COMPONENTS_SYNC_SESSIONS_SESSIONS_SYNC_MANAGER_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 101 matching lines @@
   }
 
   FaviconCache* GetFaviconCache();
 
   // Triggers garbage collection of stale sessions (as defined by
   // |stale_session_threshold_days_|). This is called every time we see new
   // sessions data downloaded (sync cycles complete).
   void DoGarbageCollection();
 
  private:
-  // Track links between a tab id and it's sync tab node id and url. The tab
-  // node id is not mutable, as the entity backing a tab should never change
-  // during runtime. The url can be updated as navigations are performed.
+  // Keep all the links to local tab data in one place. A tab_node_id and tab
+  // must be passed at creation. The tab_node_id is not mutable, although
+  // all other fields are.
   class TabLink {
    public:
-    explicit TabLink(int tab_node_id) : tab_node_id_(tab_node_id) {}
+    TabLink(int tab_node_id, const SyncedTabDelegate* tab)
+        : tab_node_id_(tab_node_id), tab_(tab) {}
 
+    void set_tab(const SyncedTabDelegate* tab) { tab_ = tab; }
     void set_url(const GURL& url) { url_ = url; }
 
     int tab_node_id() const { return tab_node_id_; }
+    const SyncedTabDelegate* tab() const { return tab_; }
     const GURL& url() const { return url_; }
 
    private:
     // The id for the sync node this tab is stored in.
     const int tab_node_id_;
 
+    // The tab object itself.
+    const SyncedTabDelegate* tab_;
+
     // The currently visible url of the tab (used for syncing favicons).
     GURL url_;
 
     DISALLOW_COPY_AND_ASSIGN(TabLink);
   };
 
   // Container for accessing local tab data by tab id.
   typedef std::map<SessionID::id_type, linked_ptr<TabLink>> TabLinksMap;
 
   friend class extensions::ExtensionSessionsTest;
@@ skipping 22 matching lines @@
                            CheckPrerenderedWebContentsSwap);
   FRIEND_TEST_ALL_PREFIXES(SessionsSyncManagerTest,
                            AssociateWindowsDontReloadTabs);
   FRIEND_TEST_ALL_PREFIXES(SessionsSyncManagerTest, SwappedOutOnRestore);
   FRIEND_TEST_ALL_PREFIXES(SessionsSyncManagerTest,
                            ProcessRemoteDeleteOfLocalSession);
   FRIEND_TEST_ALL_PREFIXES(SessionsSyncManagerTest, SetVariationIds);
 
   void InitializeCurrentMachineTag();
 
-  // Load and add window or tab data from synced specifics to our internal
+  // Load and add window or tab data for a foreign session to our internal
   // tracking.
-  void UpdateTrackerWithSpecifics(const sync_pb::SessionSpecifics& specifics,
-                                  const base::Time& modification_time);
+  void UpdateTrackerWithForeignSession(
+      const sync_pb::SessionSpecifics& specifics,
+      const base::Time& modification_time);
 
   // Returns true if |sync_data| contained a header node for the current
-  // machine, false otherwise. |new_changes| is a link to the SyncChange
-  // pipeline that exists in the caller's context. This function will append
-  // necessary changes for processing later.
+  // machine, false otherwise. |restored_tabs| is a filtered tab-only
+  // subset of |sync_data| returned by this function for convenience.
+  // |new_changes| is a link to the SyncChange pipeline that exists in the
+  // caller's context. This function will append necessary changes for
+  // processing later.
   bool InitFromSyncModel(const syncer::SyncDataList& sync_data,
+                         syncer::SyncDataList* restored_tabs,
                          syncer::SyncChangeList* new_changes);
 
   // Helper to construct a deletion SyncChange for a *tab node*.
   // Caller should check IsValid() on the returned change, as it's possible
   // this node could not be deleted.
   syncer::SyncChange TombstoneTab(const sync_pb::SessionSpecifics& tab);
 
   // Helper method to load the favicon data from the tab specifics. If the
   // favicon is valid, stores the favicon data into the favicon cache.
   void RefreshFaviconVisitTimesFromForeignTab(
@@ skipping 28 matching lines @@
                                        sessions::SessionWindow* session_window);
 
   // Resync local window information. Updates the local sessions header node
   // with the status of open windows and the order of tabs they contain. Should
   // only be called for changes that affect a window, not a change within a
   // single tab.
   //
   // RELOAD_TABS will additionally cause a resync of all tabs (same as calling
   // AssociateTabs with a vector of all tabs).
   //
+  // |restored_tabs| is a filtered tab-only subset of initial sync data, if
+  // available (during MergeDataAndStartSyncing). It can be used to obtain
+  // baseline SessionSpecifics for tabs we can't fully associate any other
+  // way because they don't yet have a WebContents.
+  //
   // Returns: false if the local session's sync nodes were deleted and
   // reassociation is necessary, true otherwise.
   //
   // |change_output| *must* be provided as a link to the SyncChange pipeline
   // that exists in the caller's context. This function will append necessary
   // changes for processing later.
   enum ReloadTabsOption { RELOAD_TABS, DONT_RELOAD_TABS };
   void AssociateWindows(ReloadTabsOption option,
+                        const syncer::SyncDataList& restored_tabs,
                         syncer::SyncChangeList* change_output);
 
   // Loads and reassociates the local tabs referenced in |tabs|.
   // |change_output| *must* be provided as a link to the SyncChange pipeline
   // that exists in the caller's context. This function will append necessary
   // changes for processing later.
   void AssociateTab(SyncedTabDelegate* const tab,
                     syncer::SyncChangeList* change_output);
 
   // Set |session_tab| from |tab_delegate| and |mtime|.
   void SetSessionTabFromDelegate(const SyncedTabDelegate& tab_delegate,
                                  base::Time mtime,
                                  sessions::SessionTab* session_tab);
 
   // Sets |variation_ids| field of |session_tab| with the ids of the currently
   // assigned variations which should be sent to sync.
   static void SetVariationIds(sessions::SessionTab* session_tab);
 
   // Populates |specifics| based on the data in |tab_delegate|.
   void LocalTabDelegateToSpecifics(const SyncedTabDelegate& tab_delegate,
                                    sync_pb::SessionSpecifics* specifics);
 
   // It's possible that when we associate windows, tabs aren't all loaded
   // into memory yet (e.g on android) and we don't have a WebContents. In this
   // case we can't do a full association, but we still want to update tab IDs
   // as they may have changed after a session was restored.  This method
   // compares new_tab_id and new_window_id against the previously persisted tab
   // ID and window ID (from our TabNodePool) and updates them if either differs.
+  // |restored_tabs| is a filtered tab-only subset of initial sync data, if
+  // available (during MergeDataAndStartSyncing). It can be used to obtain
+  // baseline SessionSpecifics for tabs we can't fully associate any other
+  // way because they don't yet have a WebContents.
+  // TODO(tim): Bug 98892. We should be able to test this for this on android
+  // even though we didn't have tests for old API-based sessions sync.
   void AssociateRestoredPlaceholderTab(
       const SyncedTabDelegate& tab_delegate,
       SessionID::id_type new_tab_id,
       SessionID::id_type new_window_id,
+      const syncer::SyncDataList& restored_tabs,
       syncer::SyncChangeList* change_output);
 
   // Stops and re-starts syncing to rebuild association mappings.
   // See |local_tab_pool_out_of_sync_|.
   void RebuildAssociations();
 
   // Validates the content of a SessionHeader protobuf.
   // Returns false if validation fails.
   static bool IsValidSessionHeader(const sync_pb::SessionHeader& header);
 
@@ skipping 65 matching lines @@
 
   // Callback to inform sync that a sync data refresh is requested.
   base::Closure datatype_refresh_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionsSyncManager);
 };
 
 }  // namespace sync_sessions
 
 #endif  // COMPONENTS_SYNC_SESSIONS_SESSIONS_SYNC_MANAGER_H_