[Sync] Add per-navigation timestamps/unique ids to tab sync.

chrome/browser/sync/glue/session_model_associator.h

Index: chrome/browser/sync/glue/session_model_associator.h
diff --git a/chrome/browser/sync/glue/session_model_associator.h b/chrome/browser/sync/glue/session_model_associator.h
index 45663d22cd6829deaf2fd471df6615d8158c887f..99c2966fdd75b719be53a3f05c4f6fe7273dbcd0 100644
--- a/chrome/browser/sync/glue/session_model_associator.h
+++ b/chrome/browser/sync/glue/session_model_associator.h
@@ -36,6 +36,10 @@ class Prefservice;
 class Profile;
 class ProfileSyncService;
 
+namespace content {
+class NavigationEntry;
+}  // namespace content
+
 namespace sync_api {
 class BaseTransaction;
 class ReadNode;
@@ -224,7 +228,13 @@ class SessionModelAssociator
   // Callback for when the session name has been computed.
   void OnSessionNameInitialized(const std::string& name);
 
+  // If a valid favicon for the page at |url| is found, fills |png_favicon| with
+  // the png-encoded image and returns true. Else, returns false.
+  bool GetSyncedFaviconForPageURL(const std::string& url,
+                                  std::string* png_favicon) const;
+
  private:
+  friend class SyncSessionModelAssociatorTest;
   FRIEND_TEST_ALL_PREFIXES(ProfileSyncServiceSessionTest, WriteSessionToNode);
   FRIEND_TEST_ALL_PREFIXES(ProfileSyncServiceSessionTest,
                            WriteFilledSessionToNode);
@@ -286,6 +296,7 @@ class SessionModelAssociator
 
   // A pool for managing free/used tab sync nodes. Performs lazy creation
   // of sync nodes when necessary.
+  // TODO(zea): pull this into it's own file.

[Andrew T Wilson (Slow), 2012/04/23 23:43:11]

nit: it's->its

[Nicolas Zea, 2012/04/24 22:09:49]

Done.

   class TabNodePool {
    public:
     explicit TabNodePool(ProfileSyncService* sync_service);
@@ -400,6 +411,22 @@ class SessionModelAssociator
   bool WriteTabContentsToSyncModel(TabLink* tab_link,
                                    SyncError* error);
 
+  // Decrements the favicon usage counters for the favicon used by |page_url|.
+  // Deletes the favicon and associated pages from the favicon usage maps
+  // if no page is found to be referring to the favicon anymore.
+  void DecrementAndCleanFaviconForURL(std::string page_url);
+
+  // Helper method to build sync's tab specifics from a newly modified
+  // tab, window, and the locally stored previous tab data. After completing,
+  // |prev_tab| will be updated to reflect the current data, |sync_tab| will
+  // be filled with the tab data (preserving old timestamps as necessary), and
+  // |new_url| will be the tab's current url.
+  void AssociateTabContents(const SyncedWindowDelegate& window,
+                            const SyncedTabDelegate& new_tab,
+                            SyncedSessionTab* prev_tab,
+                            sync_pb::SessionTab* sync_tab,
+                            GURL* new_url);
+
   // Load the favicon for the tab specified by |tab_link|. Will cancel any
   // outstanding request for this tab. OnFaviconDataAvailable(..) will be called
   // when the load completes.
@@ -429,20 +456,21 @@ class SessionModelAssociator
   // Used to populate a session tab from the session specifics tab provided.
   static void PopulateSessionTabFromSpecifics(const sync_pb::SessionTab& tab,
                                               const base::Time& mtime,
-                                              SessionTab* session_tab);
+                                              SyncedSessionTab* session_tab);
 
-  // Helper method to take the favicon data in a foreign tab and store it
-  // into the history db.
+  // Helper method to load the favicon data from the tab specifics. If the
+  // favicon is valid, stores it in |synced_favicons_|, increments
+  // |synced_favicon_usage_| and updates |synced_favicon_pages_| appropriately.
   void LoadForeignTabFavicon(const sync_pb::SessionTab& tab);
 
-  // Used to populate a session tab from the session specifics tab provided.
+  // Append a new navigation from sync specifics onto |tab| navigation vectors.
   static void AppendSessionTabNavigation(
      const sync_pb::TabNavigation& navigation,
-     std::vector<TabNavigation>* navigations);
+     SyncedSessionTab* tab);
 
   // Populates the navigation portion of the session specifics.
   static void PopulateSessionSpecificsNavigation(
-     const TabNavigation* navigation,
+     const content::NavigationEntry& navigation,
      sync_pb::TabNavigation* tab_navigation);
 
   // Returns true if this tab belongs to this profile and belongs to a window,
@@ -456,6 +484,9 @@ class SessionModelAssociator
   bool TabHasValidEntry(const SyncedTabDelegate& tab) const;
 
   // For testing only.
+  size_t NumFaviconsForTesting() const;
+
+  // For testing only.
   void QuitLoopForSubtleTesting();
 
   // Unique client tag.
@@ -503,6 +534,20 @@ class SessionModelAssociator
   // SessionID for the tab whose favicon is being set.
   CancelableRequestConsumerTSimple<SessionID::id_type> load_consumer_;
 
+  // Synced favicon storage and tracking.
+  // Map of favicon URL -> favicon data for favicons synced from other clients.
+  // Favicons are stored as png-encoded strings.
+  // TODO(zea): if this becomes expensive memory-wise, reconsider using the
+  // favicon service instead. For now, this is simpler due to the history
+  // backend not properly supporting expiration of synced favicons.
+  // See crbug.com/122890.
+  std::map<std::string, linked_ptr<std::string> > synced_favicons_;
+  // Map of favicon URL -> usage count. When the count reaches zero, we can
+  // safely delete the favicon as no tabs are referring to it anymore.
+  std::map<std::string, size_t> synced_favicon_usage_;
+  // Map of page URL -> favicon url.
+  std::map<std::string, std::string> synced_favicon_pages_;
+
   DISALLOW_COPY_AND_ASSIGN(SessionModelAssociator);
 };