WORK IN PROGRESS.

chrome/browser/extensions/extension_settings.cc

Index: chrome/browser/extensions/extension_settings.cc
diff --git a/chrome/browser/extensions/extension_settings.cc b/chrome/browser/extensions/extension_settings.cc
index a35fb5bf81bfa1a3a60e61137b8deb153839203f..b0bdc87f71858f0c95cf42b6e23358774824cdfd 100644
--- a/chrome/browser/extensions/extension_settings.cc
+++ b/chrome/browser/extensions/extension_settings.cc
@@ -13,15 +13,16 @@
 #include "chrome/browser/extensions/extension_settings_leveldb_storage.h"
 #include "chrome/browser/extensions/extension_settings_noop_storage.h"
 #include "chrome/browser/extensions/extension_settings_storage_cache.h"
+#include "chrome/browser/extensions/syncable_extension_settings_storage.h"
 #include "third_party/leveldb/include/leveldb/iterator.h"
 #include "third_party/leveldb/include/leveldb/write_batch.h"
 
 ExtensionSettings::ExtensionSettings(const FilePath& base_path)
-    : base_path_(base_path) {
+    : base_path_(base_path), sync_processor_(NULL) {
 }
 
 ExtensionSettings::~ExtensionSettings() {
-  std::map<std::string, ExtensionSettingsStorage*>::iterator it;
+  std::map<std::string, SyncableExtensionSettingsStorage*>::iterator it;
   for (it = storage_objs_.begin(); it != storage_objs_.end(); ++it) {
     it->second->DeleteSoon();
   }
@@ -52,14 +53,14 @@ void ExtensionSettings::GetStorageForTesting(
 
 bool ExtensionSettings::GetExistingStorage(
     const std::string& extension_id, const Callback& callback) {
-  std::map<std::string, ExtensionSettingsStorage*>::iterator existing =
+  std::map<std::string, SyncableExtensionSettingsStorage*>::iterator existing =
       storage_objs_.find(extension_id);
   if (existing == storage_objs_.end()) {
     // No existing storage.
     return false;
   }
   // Existing storage.  Reply with that.
-  ExtensionSettingsStorage* storage = existing->second;
+  SyncableExtensionSettingsStorage* storage = existing->second;
   DCHECK(storage != NULL);
   MessageLoop::current()->PostTask(
       FROM_HERE,
@@ -72,7 +73,7 @@ bool ExtensionSettings::GetExistingStorage(
 }
 
 void ExtensionSettings::RunWithStorage(
-    Callback* callback, ExtensionSettingsStorage* storage) {
+    Callback* callback, SyncableExtensionSettingsStorage* storage) {
   callback->Run(storage);
   delete callback;
 }
@@ -103,7 +104,8 @@ void ExtensionSettings::CreateStorageOnFileThread(
     bool cached,
     const Callback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  ExtensionSettingsStorage* storage = CreateStorage(extension_id, type, cached);
+  SyncableExtensionSettingsStorage* storage =
+      CreateStorage(extension_id, type, cached);
   if (storage == NULL && fallback_type != type) {
     storage = CreateStorage(extension_id, fallback_type, cached);
   }
@@ -119,7 +121,7 @@ void ExtensionSettings::CreateStorageOnFileThread(
           callback));
 }
 
-ExtensionSettingsStorage* ExtensionSettings::CreateStorage(
+SyncableExtensionSettingsStorage* ExtensionSettings::CreateStorage(
     const std::string& extension_id,
     ExtensionSettingsStorage::Type type,
     bool cached) {
@@ -136,20 +138,26 @@ ExtensionSettingsStorage* ExtensionSettings::CreateStorage(
     default:
       NOTREACHED();
   }
-  if (storage != NULL && cached) {
+  if (storage == NULL) {
+    return NULL;
+  }
+  if (cached) {
     storage = new ExtensionSettingsStorageCache(storage);
   }
-  return storage;
+  // Always send changes to sync.  The merge algorithm is such that local data
+  // will be overwritten by sync data, so even if it's purely in-memory storage
+  // the settings will be consistent across browser restarts.
+  return new SyncableExtensionSettingsStorage(extension_id, storage);
 }
 
 void ExtensionSettings::EndCreationOfStorage(
     const std::string& extension_id,
-    ExtensionSettingsStorage* storage,
+    SyncableExtensionSettingsStorage* storage,
     const Callback& callback) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   // Cache the result now.  To avoid a race condition, check again to see
   // whether a storage has been created already; if so, use that one.
-  std::map<std::string, ExtensionSettingsStorage*>::iterator existing =
+  std::map<std::string, SyncableExtensionSettingsStorage*>::iterator existing =
       storage_objs_.find(extension_id);
   if (existing == storage_objs_.end()) {
     storage_objs_[extension_id] = storage;
@@ -158,5 +166,148 @@ void ExtensionSettings::EndCreationOfStorage(
     storage = existing->second;
     DCHECK(storage != NULL);
   }
+  if (sync_processor_ != NULL) {
+    StartSyncingStorage(extension_id, storage);
+  }
   callback.Run(storage);
 }
+
+SyncDataList ExtensionSettings::GetAllSyncData(
+    syncable::ModelType type) const {
+  // Not possible to do this synchronously, or while satisfying const, but only
+  // used for debugging so fine to ignore.
+  return SyncDataList();
+}
+
+SyncError ExtensionSettings::MergeDataAndStartSyncing(
+    syncable::ModelType type,
+    const SyncDataList& initial_sync_data,
+    SyncChangeProcessor* sync_processor) {
+  DCHECK(type == syncable::EXTENSION_SETTINGS);
+  DCHECK(sync_processor_ == NULL);
+  sync_processor_ = sync_processor;
+
+  // Unmerged sync data could conceivably be non-empty if this method is called
+  // in quick succession, before the storage creation methods return (clearing
+  // the data).  Clearing the unmerged data here is safe, it will just get
+  // repopulated with the new and correct data.
+  std::map<std::string, DictionaryValue*>::iterator unmerged_it;
+  for (unmerged_it = unmerged_sync_data_.begin();
+      unmerged_it != unmerged_sync_data_.end(); ++unmerged_it) {
+    delete unmerged_it->second;
+  }
+  unmerged_sync_data_.clear();
+
+  // Merge algorithm when starting to sync: for each extension, if there are no
+  // sycned settings yet, push local settings to sync.  Otherwise, completely
+  // overwrite local settings with those from sync.
+  //
+  // Firstly group the initial data per extension.
+  for (SyncDataList::const_iterator it = initial_sync_data.begin();
+      it != initial_sync_data.end(); ++it) {
+    ExtensionSettingsSyncData data(*it);
+    if (data.value() == NULL) {
+      LOG(WARNING) << "NULL value in sync data";
+      continue;
+    }
+    DictionaryValue* sync_data = unmerged_sync_data_[data.extension_id()];
+    if (sync_data == NULL) {
+      sync_data = new DictionaryValue();
+      unmerged_sync_data_[data.extension_id()] = sync_data;
+    }
+    DCHECK(!sync_data->HasKey(data.key())) <<
+        "Duplicate settings for " << data.extension_id() << "/" << data.key();
+    sync_data->Set(data.key(), data.value()->DeepCopy());
+  }
+
+  // Immediately push sync state to local for existing storage areas.
+  std::map<std::string, SyncableExtensionSettingsStorage*>::iterator storage_it;
+  for (storage_it = storage_objs_.begin();
+      storage_it != storage_objs_.end(); ++storage_it) {
+    StartSyncingStorage(storage_it->first, storage_it->second);
+  }
+
+  // Asynchronously push sync state to local for the remaining settings.
+  for (unmerged_it = unmerged_sync_data_.begin();
+      unmerged_it != unmerged_sync_data_.end(); ++unmerged_it) {
+    // StartSyncingStorage will be called from EndCreationOfStorage, so the
+    // actual callback from getting the storage doesn't need to do anything.
+    GetStorage(
+        unmerged_it->first,
+        base::Bind(
+            &ExtensionSettings::AssertNoSyncData,
+            this,
+            unmerged_it->first));
+  }
+
+  return SyncError();
+}
+
+void ExtensionSettings::AssertNoSyncData(
+    const std::string& extension_id,
+    SyncableExtensionSettingsStorage* storage) {
+  DCHECK_EQ(0u, unmerged_sync_data_.count(extension_id));
+}
+
+void ExtensionSettings::StartSyncingStorage(
+    const std::string& extension_id,
+    SyncableExtensionSettingsStorage* storage) {
+  DCHECK(sync_processor_ != NULL);
+  scoped_ptr<DictionaryValue> sync_data(unmerged_sync_data_[extension_id]);
+  unmerged_sync_data_.erase(extension_id);
+  if (sync_data.get() == NULL) {
+    DictionaryValue no_data;
+    storage->StartSyncing(no_data, sync_processor_);
+  } else {
+    storage->StartSyncing(*sync_data, sync_processor_);
+  }
+}
+
+static void CallProcessSyncChanges(
+    ExtensionSettingsSyncDataList* sync_changes,
+    SyncableExtensionSettingsStorage* storage) {
+  storage->ProcessSyncChanges(*sync_changes);
+  delete sync_changes;
+}
+
+SyncError ExtensionSettings::ProcessSyncChanges(
+    const tracked_objects::Location& from_here,
+    const SyncChangeList& sync_changes) {
+  DCHECK(sync_processor_ != NULL);
+
+  // Gather changes per extension, so that all the processing can be done from a
+  // single GetStorage() call.
+  std::map<std::string, ExtensionSettingsSyncDataList> all_sync_data;
+  for (SyncChangeList::const_iterator it = sync_changes.begin();
+      it != sync_changes.end(); ++it) {
+    ExtensionSettingsSyncData data(*it);
+    if (data.value() == NULL) {
+      LOG(WARNING) << "NULL value in sync data";
+      continue;
+    }
+    all_sync_data[data.extension_id()].push_back(data);
+  }
+
+  // Push changes to storage areas.
+  std::map<std::string, ExtensionSettingsSyncDataList>::iterator it;
+  for (it = all_sync_data.begin(); it != all_sync_data.end(); ++it) {
+    GetStorage(
+        it->first,
+        base::Bind(
+            &CallProcessSyncChanges,
+            new ExtensionSettingsSyncDataList(it->second)));
+  }
+
+  return SyncError();
+}
+
+void ExtensionSettings::StopSyncing(syncable::ModelType type) {
+  DCHECK(type == syncable::EXTENSION_SETTINGS);
+  DCHECK(sync_processor_ != NULL);
+  sync_processor_ = NULL;
+
+  std::map<std::string, SyncableExtensionSettingsStorage*>::iterator it;
+  for (it = storage_objs_.begin(); it != storage_objs_.end(); ++it) {
+    it->second->StopSyncing();
+  }
+}