Add a Restore() method to ValueStore and make StorageAPI use it

chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.cc

Index: chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.cc
diff --git a/chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.cc b/chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.cc
index f26bc2eeba57775d9fb5d358be87d73307c2777e..9ff1175bc728be18c84db4c226feba7720610e0c 100644
--- a/chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.cc
+++ b/chrome/browser/extensions/api/storage/sync_or_local_value_store_cache.cc
@@ -8,9 +8,10 @@
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/sequenced_task_runner.h"
-#include "chrome/browser/extensions/api/storage/settings_backend.h"
+#include "chrome/browser/extensions/api/storage/local_storage_backend.h"
 #include "chrome/browser/extensions/api/storage/settings_frontend.h"
 #include "chrome/browser/extensions/api/storage/settings_storage_quota_enforcer.h"
+#include "chrome/browser/extensions/api/storage/sync_storage_backend.h"
 #include "chrome/browser/extensions/api/storage/weak_unlimited_settings_storage.h"
 #include "chrome/browser/sync/glue/sync_start_util.h"
 #include "content/public/browser/browser_thread.h"
@@ -28,7 +29,7 @@ SyncOrLocalValueStoreCache::SyncOrLocalValueStoreCache(
     const SettingsStorageQuotaEnforcer::Limits& quota,
     const scoped_refptr<SettingsObserverList>& observers,
     const base::FilePath& profile_path)
-    : settings_namespace_(settings_namespace) {
+    : settings_namespace_(settings_namespace), initialized_(false) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(settings_namespace_ == settings_namespace::LOCAL ||
          settings_namespace_ == settings_namespace::SYNC);
@@ -47,24 +48,27 @@ SyncOrLocalValueStoreCache::~SyncOrLocalValueStoreCache() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 }
 
-SettingsBackend* SyncOrLocalValueStoreCache::GetAppBackend() const {
+syncer::SyncableService* SyncOrLocalValueStoreCache::GetSyncableService(
+    syncer::ModelType type) const {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(app_backend_.get());
-  return app_backend_.get();
-}
-
-SettingsBackend* SyncOrLocalValueStoreCache::GetExtensionBackend() const {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(extension_backend_.get());
-  return extension_backend_.get();
+  DCHECK(initialized_);
+  switch (type) {
+    case syncer::APP_SETTINGS:
+      return app_backend_->GetAsSyncableService();
+    case syncer::EXTENSION_SETTINGS:
+      return extension_backend_->GetAsSyncableService();
+    default:
+      NOTREACHED();
+      return NULL;
+  }
 }
 
 void SyncOrLocalValueStoreCache::RunWithValueStoreForExtension(
     const StorageCallback& callback,
     scoped_refptr<const Extension> extension) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(app_backend_.get());
-  DCHECK(extension_backend_.get());
+  DCHECK(initialized_);
+
   SettingsBackend* backend =
       extension->is_app() ? app_backend_.get() : extension_backend_.get();
   ValueStore* storage = backend->GetStorage(extension->id());
@@ -89,6 +93,7 @@ void SyncOrLocalValueStoreCache::RunWithValueStoreForExtension(
 void SyncOrLocalValueStoreCache::DeleteStorageSoon(
     const std::string& extension_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  DCHECK(initialized_);
   app_backend_->DeleteStorage(extension_id);
   extension_backend_->DeleteStorage(extension_id);
 }
@@ -99,23 +104,39 @@ void SyncOrLocalValueStoreCache::InitOnFileThread(
     const scoped_refptr<SettingsObserverList>& observers,
     const base::FilePath& profile_path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
-  DCHECK(!app_backend_.get());
-  DCHECK(!extension_backend_.get());
-  const bool local = settings_namespace_ == settings_namespace::LOCAL;
-  const base::FilePath app_path = profile_path.AppendASCII(
-      local ? extensions::kLocalAppSettingsDirectoryName
-            : extensions::kSyncAppSettingsDirectoryName);
-  const base::FilePath extension_path = profile_path.AppendASCII(
-      local ? extensions::kLocalExtensionSettingsDirectoryName
-            : extensions::kSyncExtensionSettingsDirectoryName);
-  app_backend_.reset(new SettingsBackend(
-      factory, app_path, syncer::APP_SETTINGS,
-      sync_start_util::GetFlareForSyncableService(profile_path),
-      quota, observers));
-  extension_backend_.reset(new SettingsBackend(
-      factory, extension_path, syncer::EXTENSION_SETTINGS,
-      sync_start_util::GetFlareForSyncableService(profile_path),
-      quota, observers));
+  DCHECK(!initialized_);
+  switch (settings_namespace_) {
+    case settings_namespace::LOCAL:
+      app_backend_.reset(new LocalStorageBackend(
+          factory,
+          profile_path.AppendASCII(kLocalAppSettingsDirectoryName),
+          quota));
+      extension_backend_.reset(new LocalStorageBackend(
+          factory,
+          profile_path.AppendASCII(kLocalExtensionSettingsDirectoryName),
+          quota));
+      break;
+    case settings_namespace::SYNC:
+      app_backend_.reset(new SyncStorageBackend(
+          factory,
+          profile_path.AppendASCII(kSyncAppSettingsDirectoryName),
+          quota,
+          observers,
+          syncer::APP_SETTINGS,
+          sync_start_util::GetFlareForSyncableService(profile_path)));
+      extension_backend_.reset(new SyncStorageBackend(
+          factory,
+          profile_path.AppendASCII(kSyncExtensionSettingsDirectoryName),
+          quota,
+          observers,
+          syncer::EXTENSION_SETTINGS,
+          sync_start_util::GetFlareForSyncableService(profile_path)));
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  initialized_ = true;
 }
 
 }  // namespace extensions