Migrate startup URLs pref.

chrome/browser/prefs/pref_model_associator.cc

 // 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.
 
 #include "chrome/browser/prefs/pref_model_associator.h"
 
 #include "base/auto_reset.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/location.h"
@@ skipping 30 matching lines @@
     sync_pb::EntitySpecifics* specifics) {
   if (type == syncer::PRIORITY_PREFERENCES) {
     DCHECK(!specifics->has_preference());
     return specifics->mutable_priority_preference()->mutable_preference();
   } else {
     DCHECK(!specifics->has_priority_preference());
     return specifics->mutable_preference();
   }
 }
 
+// List of migrated preference name pairs. If a preference is migrated
+// (meaning renamed) adding the old and new preference names here will ensure
+// that the sync engine knows how to deal with the synced values coming in
+// with the old name. Preference migration itself doesn't happen here. It may
+// happen in session_startup_pref.cc.
+const struct MigratedPreferences {
+  const char* const old_name;
+  const char* const new_name;
+} kMigratedPreferences[] = {
+  { prefs::kURLsToRestoreOnStartupOld, prefs::kURLsToRestoreOnStartup },
+};
+
+std::string GetOldMigratedPreferenceName(const char* preference_name) {
+  for (size_t i = 0; i < arraysize(kMigratedPreferences); ++i) {
+    if (!strcmp(kMigratedPreferences[i].new_name, preference_name))
+      return kMigratedPreferences[i].old_name;
+  }
+  return std::string();
+}
+
+std::string GetNewMigratedPreferenceName(const char* old_preference_name) {
+  for (size_t i = 0; i < arraysize(kMigratedPreferences); ++i) {
+    if (!strcmp(kMigratedPreferences[i].old_name, old_preference_name))
+      return kMigratedPreferences[i].new_name;
+  }
+  return std::string();
+}
+
+bool IsMigratedPreference(const char* preference_name) {
+  return !GetOldMigratedPreferenceName(preference_name).empty();
+}
+
+bool IsOldMigratedPreference(const char* old_preference_name) {
+  return !GetNewMigratedPreferenceName(old_preference_name).empty();
+}
+
 }  // namespace
 
 PrefModelAssociator::PrefModelAssociator(syncer::ModelType type)
     : models_associated_(false),
       processing_syncer_changes_(false),
       pref_service_(NULL),
       type_(type) {
   DCHECK(CalledOnValidThread());
   DCHECK(type_ == PREFERENCES || type_ == PRIORITY_PREFERENCES);
 }
 
 PrefModelAssociator::~PrefModelAssociator() {
   DCHECK(CalledOnValidThread());
   pref_service_ = NULL;
 
   STLDeleteContainerPairSecondPointers(synced_pref_observers_.begin(),
                                        synced_pref_observers_.end());
   synced_pref_observers_.clear();
 }
 
 void PrefModelAssociator::InitPrefAndAssociate(
     const syncer::SyncData& sync_pref,
     const std::string& pref_name,
-    syncer::SyncChangeList* sync_changes) {
+    syncer::SyncChangeList* sync_changes,
+    SyncDataPrefList* migrated_preference_list) {
   const Value* user_pref_value = pref_service_->GetUserPrefValue(
       pref_name.c_str());
   VLOG(1) << "Associating preference " << pref_name;
 
   if (sync_pref.IsValid()) {
     const sync_pb::PreferenceSpecifics& preference = GetSpecifics(sync_pref);
-    DCHECK_EQ(pref_name, preference.name());
-
+    DCHECK(pref_name == preference.name() ||
+           (IsMigratedPreference(pref_name.c_str()) &&
+            preference.name() ==
+                GetOldMigratedPreferenceName(pref_name.c_str())));
     base::JSONReader reader;
     scoped_ptr<Value> sync_value(reader.ReadToValue(preference.value()));
     if (!sync_value.get()) {
       LOG(ERROR) << "Failed to deserialize preference value: "
                  << reader.GetErrorMessage();
       return;
     }
 
     if (user_pref_value) {
       // We have both server and local values. Merge them.
@@ skipping 19 matching lines @@
       if (!sync_value->Equals(new_value.get())) {
         syncer::SyncData sync_data;
         if (!CreatePrefSyncData(pref_name, *new_value, &sync_data)) {
           LOG(ERROR) << "Failed to update preference.";
           return;
         }
         sync_changes->push_back(
             syncer::SyncChange(FROM_HERE,
                                syncer::SyncChange::ACTION_UPDATE,
                                sync_data));
+        // This preference has been migrated from an old version that must be
+        // kept in sync on older versions of Chrome.
+        if (IsMigratedPreference(pref_name.c_str()) &&
+            migrated_preference_list) {
+          if (!CreatePrefSyncData(
+                  GetOldMigratedPreferenceName(pref_name.c_str()),
+                  *new_value,
+                  &sync_data)) {
+            LOG(ERROR) << "Failed to update preference.";
+            return;
+          }
+
+          migrated_preference_list->push_back(
+              std::make_pair(GetOldMigratedPreferenceName(pref_name.c_str()),
+                             sync_data));
+        }
       }
     } else if (!sync_value->IsType(Value::TYPE_NULL)) {
       // Only a server value exists. Just set the local user value.
       pref_service_->Set(pref_name.c_str(), *sync_value);
     } else {
       LOG(WARNING) << "Sync has null value for pref " << pref_name.c_str();
     }
   } else if (user_pref_value) {
     // The server does not know about this preference and should be added
     // to the syncer's database.
     syncer::SyncData sync_data;
     if (!CreatePrefSyncData(pref_name, *user_pref_value, &sync_data)) {
       LOG(ERROR) << "Failed to update preference.";
       return;
     }
     sync_changes->push_back(
         syncer::SyncChange(FROM_HERE,
                            syncer::SyncChange::ACTION_ADD,
                            sync_data));
   } else {
     // This pref does not have a sync value but also does not have a user
     // controlled value (either it's a default value or it's policy controlled,
     // either way it's not interesting). We can ignore it. Once it gets changed,
     // we'll send the new user controlled value to the syncer.
     return;
   }
 
   // Make sure we add it to our list of synced preferences so we know what
   // the server is aware of.
   synced_preferences_.insert(pref_name);

[Nicolas Zea, 2013/10/10 17:44:14]

I don't think this will ever add the old pref name to the synced_preferences_
list, which means that the below check in synced_preferences_ for the name won't
work properly. It probably makes sense to have this insert preference.name()
now.

[robertshield, 2013/10/10 20:06:21]

Ah true, the pref will still get synced but subsequent updates will again run as
ADD actions which I guess won't work as desired.

It probably makes sense to have this insert preference.name()
I'm not 100% sure I understand this last bit. Do you mean rather that I should
insert GetOldMigratedPreferenceName(pref_name) into synced_preferences_
(presumably ~line 173), or do you mean something else?

[Nicolas Zea, 2013/10/10 20:35:09]

Basically, if the preference sync is passing to the model associator is the old
preference, we need to somehow know that sync has an entity for the old
preference already. preference.name() matches whatever sync has (pref_name is
the one that would be the migrated pref), so I think it makes sense to insert
preference.name() here.

[robertshield, 2013/10/11 18:29:31]

Done.

   return;
 }
 
 syncer::SyncMergeResult PrefModelAssociator::MergeDataAndStartSyncing(
     syncer::ModelType type,
     const syncer::SyncDataList& initial_sync_data,
     scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
     scoped_ptr<syncer::SyncErrorFactory> sync_error_factory) {
   DCHECK_EQ(type_, type);
   DCHECK(CalledOnValidThread());
   DCHECK(pref_service_);
   DCHECK(!sync_processor_.get());
   DCHECK(sync_processor.get());
   DCHECK(sync_error_factory.get());
   syncer::SyncMergeResult merge_result(type);
   sync_processor_ = sync_processor.Pass();
   sync_error_factory_ = sync_error_factory.Pass();
 
   syncer::SyncChangeList new_changes;
   std::set<std::string> remaining_preferences = registered_preferences_;
 
+  // Maintains a list of old migrated preference names that we wish to sync.
+  // Keep track of these in a list such that when the preference iteration
+  // loops below are complete we can go back and determine whether
+  SyncDataPrefList migrated_preference_list;
+
   // Go through and check for all preferences we care about that sync already
   // knows about.
   for (syncer::SyncDataList::const_iterator sync_iter =
            initial_sync_data.begin();
        sync_iter != initial_sync_data.end();
        ++sync_iter) {
     DCHECK_EQ(type_, sync_iter->GetDataType());
 
     const sync_pb::PreferenceSpecifics& preference = GetSpecifics(*sync_iter);
-    const std::string& sync_pref_name = preference.name();
+    std::string sync_pref_name = preference.name();
 
     if (remaining_preferences.count(sync_pref_name) == 0) {
-      // We're not syncing this preference locally, ignore the sync data.
-      // TODO(zea): Eventually we want to be able to have the syncable service
-      // reconstruct all sync data for it's datatype (therefore having
-      // GetAllSyncData be a complete representation). We should store this data
-      // somewhere, even if we don't use it.
-      continue;
+      if (IsOldMigratedPreference(sync_pref_name.c_str())) {
+        // This old pref name is not syncable locally anymore but we accept
+        // changes from other Chrome installs of previous versions and migrate
+        // them to the new name. Note that we will be merging any differences
+        // between the new and old values and sync'ing them back.
+        sync_pref_name = GetNewMigratedPreferenceName(sync_pref_name.c_str());
+      } else {
+        // We're not syncing this preference locally, ignore the sync data.
+        // TODO(zea): Eventually we want to be able to have the syncable service
+        // reconstruct all sync data for its datatype (therefore having
+        // GetAllSyncData be a complete representation). We should store this
+        // data somewhere, even if we don't use it.
+        continue;
+      }
+    } else {
+      remaining_preferences.erase(sync_pref_name);
     }
-
-    remaining_preferences.erase(sync_pref_name);
-    InitPrefAndAssociate(*sync_iter, sync_pref_name, &new_changes);
+    InitPrefAndAssociate(*sync_iter, sync_pref_name, &new_changes,
+                         &migrated_preference_list);
   }
 
   // Go through and build sync data for any remaining preferences.
   for (std::set<std::string>::iterator pref_name_iter =
           remaining_preferences.begin();
        pref_name_iter != remaining_preferences.end();
        ++pref_name_iter) {
-    InitPrefAndAssociate(syncer::SyncData(), *pref_name_iter, &new_changes);
+    InitPrefAndAssociate(syncer::SyncData(), *pref_name_iter, &new_changes,
+                         &migrated_preference_list);
+  }
+
+  // Now go over any migrated preference names and build sync data for them too.
+  for (SyncDataPrefList::const_iterator migrated_pref_iter =
+          migrated_preference_list.begin();
+       migrated_pref_iter != migrated_preference_list.end();
+       ++migrated_pref_iter) {
+    syncer::SyncChange::SyncChangeType change_type =
+        (synced_preferences_.count(migrated_pref_iter->first) == 0) ?
+            syncer::SyncChange::ACTION_ADD :
+            syncer::SyncChange::ACTION_UPDATE;
+    new_changes.push_back(
+        syncer::SyncChange(FROM_HERE, change_type, migrated_pref_iter->second));
   }
 
   // Push updates to sync.
   merge_result.set_error(
       sync_processor_->ProcessSyncChanges(FROM_HERE, new_changes));
   if (merge_result.error().IsSet())
     return merge_result;
 
   models_associated_ = true;
   pref_service_->OnIsSyncingChanged();
   return merge_result;
 }
 
 void PrefModelAssociator::StopSyncing(syncer::ModelType type) {
   DCHECK_EQ(type_, type);
   models_associated_ = false;
   sync_processor_.reset();
   sync_error_factory_.reset();
   pref_service_->OnIsSyncingChanged();
 }
 
 scoped_ptr<Value> PrefModelAssociator::MergePreference(
     const std::string& name,
     const Value& local_value,
     const Value& server_value) {
-  if (name == prefs::kURLsToRestoreOnStartup) {
+  // This function special cases preferences individually, so don't attempt
+  // to merge for all migrated values.
+  if (name == prefs::kURLsToRestoreOnStartup ||
+      name == prefs::kURLsToRestoreOnStartupOld) {
     return scoped_ptr<Value>(MergeListValues(local_value, server_value)).Pass();
   }
 
   if (name == prefs::kContentSettingsPatternPairs) {
     return scoped_ptr<Value>(
         MergeDictionaryValues(local_value, server_value)).Pass();
   }
 
   // If this is not a specially handled preference, server wins.
   return scoped_ptr<Value>(server_value.DeepCopy()).Pass();
@@ skipping 142 matching lines @@
     // TODO(zea): consider taking some further action such as erasing the bad
     // data.
     if (!value.get())
       continue;
 
     // It is possible that we may receive a change to a preference we do not
     // want to sync. For example if the user is syncing a Mac client and a
     // Windows client, the Windows client does not support
     // kConfirmToQuitEnabled. Ignore updates from these preferences.
     const char* pref_name = name.c_str();
+    std::string new_name;
+    // We migrated this preference name, so do as if the name had not changed.
+    if (IsOldMigratedPreference(pref_name)) {
+      new_name = GetNewMigratedPreferenceName(pref_name);
+      pref_name = new_name.c_str();
+    }
+
     if (!IsPrefRegistered(pref_name))
       continue;
 
     const PrefService::Preference* pref =
         pref_service_->FindPreference(pref_name);
     DCHECK(pref);
 
     // This will only modify the user controlled value store, which takes
     // priority over the default value but is ignored if the preference is
     // policy controlled.
@@ skipping 88 matching lines @@
   }
 
   base::AutoReset<bool> processing_changes(&processing_syncer_changes_, true);
 
   NotifySyncedPrefObservers(name, false /*from_sync*/);
 
   if (synced_preferences_.count(name) == 0) {
     // Not in synced_preferences_ means no synced data. InitPrefAndAssociate(..)
     // will determine if we care about its data (e.g. if it has a default value
     // and hasn't been changed yet we don't) and take care syncing any new data.
-    InitPrefAndAssociate(syncer::SyncData(), name, &changes);
+    InitPrefAndAssociate(syncer::SyncData(), name, &changes, NULL);
   } else {
     // We are already syncing this preference, just update it's sync node.
     syncer::SyncData sync_data;
     if (!CreatePrefSyncData(name, *preference->GetValue(), &sync_data)) {
       LOG(ERROR) << "Failed to update preference.";
       return;
     }
     changes.push_back(
         syncer::SyncChange(FROM_HERE,
                            syncer::SyncChange::ACTION_UPDATE,
                            sync_data));
+    // This preference has been migrated from an old version that must be kept
+    // in sync on older versions of Chrome.
+    if (IsMigratedPreference(name.c_str())) {
+      std::string old_pref_name = GetOldMigratedPreferenceName(name.c_str());
+      if (!CreatePrefSyncData(old_pref_name,
+                              *preference->GetValue(),
+                              &sync_data)) {
+        LOG(ERROR) << "Failed to update preference.";
+        return;
+      }
+
+      syncer::SyncChange::SyncChangeType change_type =
+          (synced_preferences_.count(name) == 0) ?
+              syncer::SyncChange::ACTION_ADD :
+              syncer::SyncChange::ACTION_UPDATE;
+      changes.push_back(
+          syncer::SyncChange(FROM_HERE, change_type, sync_data));
+    }
   }
 
   syncer::SyncError error =
       sync_processor_->ProcessSyncChanges(FROM_HERE, changes);
 }
 
 void PrefModelAssociator::SetPrefService(PrefServiceSyncable* pref_service) {
   DCHECK(pref_service_ == NULL);
   pref_service_ = pref_service;
 }
 
 void PrefModelAssociator::NotifySyncedPrefObservers(const std::string& path,
                                                     bool from_sync) const {
   SyncedPrefObserverMap::const_iterator observer_iter =
       synced_pref_observers_.find(path);
   if (observer_iter == synced_pref_observers_.end())
     return;
   SyncedPrefObserverList* observers = observer_iter->second;
   FOR_EACH_OBSERVER(SyncedPrefObserver, *observers,
                     OnSyncedPrefChanged(path, from_sync));
 }