[Sync] Add interface and backend impl for typed URL syncable service

chrome/browser/history/typed_url_syncable_service.h

Index: chrome/browser/history/typed_url_syncable_service.h
diff --git a/chrome/browser/history/typed_url_syncable_service.h b/chrome/browser/history/typed_url_syncable_service.h
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+// Copyright (c) 2013 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_HISTORY_TYPED_URL_SYNCABLE_SERVICE_H_
+#define CHROME_BROWSER_HISTORY_TYPED_URL_SYNCABLE_SERVICE_H_
+
+#include <set>
+#include <vector>
+
+#include "chrome/browser/history/history_notifications.h"
+#include "chrome/browser/history/history_types.h"
+#include "content/public/browser/notification_types.h"
+#include "sync/api/sync_change.h"
+#include "sync/api/sync_data.h"
+#include "sync/api/sync_error.h"
+#include "sync/api/sync_error_factory.h"
+#include "sync/api/syncable_service.h"
+
+class GURL;
+class TypedUrlSyncableServiceTest;
+
+namespace base {
+class MessageLoop;
+};
+
+namespace history {
+class HistoryBackend;
+class URLRow;
+};
+
+namespace sync_pb {
+class TypedUrlSpecifics;
+};
+
+// extern const char kTypedUrlTag[];
+
+class TypedUrlSyncableService : public syncer::SyncableService {

[Andrew T Wilson (Slow), 2013/04/09 12:48:30]

Should this be inside the history namespace?

+ public:
+  explicit TypedUrlSyncableService(history::HistoryBackend* history_backend);
+  virtual ~TypedUrlSyncableService();
+
+  static syncer::ModelType model_type() { return syncer::TYPED_URLS; }
+
+  // syncer::SyncableService implementation.
+  virtual syncer::SyncMergeResult MergeDataAndStartSyncing(
+      syncer::ModelType type,
+      const syncer::SyncDataList& initial_sync_data,
+      scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
+      scoped_ptr<syncer::SyncErrorFactory> error_handler) OVERRIDE;
+  virtual void StopSyncing(syncer::ModelType type) OVERRIDE;
+  virtual syncer::SyncDataList GetAllSyncData(
+      syncer::ModelType type) const OVERRIDE;
+  virtual syncer::SyncError ProcessSyncChanges(
+      const tracked_objects::Location& from_here,
+      const syncer::SyncChangeList& change_list) OVERRIDE;
+
+  // Called directly by HistoryBackend when local url data changes.
+  void OnUrlsModified(history::URLsModifiedDetails* details);
+  void OnUrlVisited(history::URLVisitedDetails* details);
+  void OnUrlsDeleted(history::URLsDeletedDetails* details);
+
+ protected:
+  void GetSyncedUrls(std::set<GURL>* urls) {
+    urls->insert(synced_typed_urls_.begin(), synced_typed_urls_.end());
+  }
+
+ private:
+  typedef std::vector<std::pair<history::URLID, history::URLRow> >
+      TypedUrlUpdateVector;
+  typedef std::vector<std::pair<GURL, std::vector<history::VisitInfo> > >
+      TypedUrlVisitVector;
+
+  // This is a helper map used only in Merge/Process* functions. The lifetime
+  // of the iterator is longer than the map object.
+  typedef std::map<GURL, std::pair<syncer::SyncChange::SyncChangeType,
+                                   history::URLRows::iterator> > TypedUrlMap;
+  // This is a helper map used to associate visit vectors from the history db
+  // to the typed urls in the above map.
+  typedef std::map<GURL, history::VisitVector> UrlVisitVectorMap;
+
+  // Helper function that determines if we should ignore a URL for the purposes
+  // of sync, because it contains invalid data.
+  bool ShouldIgnoreUrl(const GURL& url);
+
+  // Returns true if the caller should sync as a result of the passed visit
+  // notification. We use this to throttle the number of sync changes we send
+  // to the server so we don't hit the server for every
+  // single typed URL visit.
+  bool ShouldSyncVisit(history::URLVisitedDetails* details);
+
+  // Utility routine that either updates an existing sync node or creates a
+  // new one for the passed |typed_url| if one does not already exist. Returns
+  // false and sets an unrecoverable error if the operation failed.
+  bool CreateOrUpdateSyncNode(history::URLRow typed_url,
+                              syncer::SyncChangeList* changes);
+
+  void AddTypedUrlToChangeList(
+    syncer::SyncChange::SyncChangeType change_type,
+    const history::URLRow& row,
+    const history::VisitVector& visits,
+    std::string title,
+    syncer::SyncChangeList* change_list);
+
+  // Converts the passed URL information to a TypedUrlSpecifics structure for
+  // writing to the sync DB
+  static void WriteToTypedUrlSpecifics(const history::URLRow& url,
+                                       const history::VisitVector& visits,
+                                       sync_pb::TypedUrlSpecifics* specifics);
+
+  // Fetches visits from the history DB corresponding to the passed URL. This
+  // function compensates for the fact that the history DB has rather poor data
+  // integrity (duplicate visits, visit timestamps that don't match the
+  // last_visit timestamp, huge data sets that exhaust memory when fetched,
+  // etc) by modifying the passed |url| object and |visits| vector.
+  // Returns false if we could not fetch the visits for the passed URL, and
+  // tracks DB error statistics internally for reporting via UMA.
+  virtual bool FixupURLAndGetVisits(history::URLRow* url,
+                                    history::VisitVector* visits);
+
+  std::set<GURL> synced_typed_urls_;

[Andrew T Wilson (Slow), 2013/04/09 12:48:30]

So we keep an in-memory copy of all currently synced typed URLs now? Should we
be concerned about the memory overhead? 

+
+  history::HistoryBackend* const history_backend_;
+
+  // Whether we're currently processing changes from the syncer. While this is
+  // true, we ignore any local url changes, since we triggered them.
+  bool processing_syncer_changes_;
+
+  // We receive ownership of |sync_processor_| and |error_handler_| in
+  // MergeDataAndStartSyncing() and destroy them in StopSyncing().
+  scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
+  scoped_ptr<syncer::SyncErrorFactory> sync_error_handler_;
+
+  // Statistics for the purposes of tracking the percentage of DB accesses that
+  // fail for each client via UMA.
+  int num_db_accesses_;
+  int num_db_errors_;
+
+  base::MessageLoop* expected_loop_;
+
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           AddLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           UpdateLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           LinkVisitLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           TypedVisitLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           DeleteLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           DeleteAllLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           MaxVisitLocalTypedUrlAndSync);
+  FRIEND_TEST_ALL_PREFIXES(TypedUrlSyncableServiceTest,
+                           ThrottleVisitLocalTypedUrlSync);
+
+  DISALLOW_COPY_AND_ASSIGN(TypedUrlSyncableService);
+};
+
+#endif  // CHROME_BROWSER_HISTORY_TYPED_URL_SYNCABLE_SERVICE_H_