Use Observer to notify of WebDB load instead of callbacks

components/webdata/common/web_data_service_backend.cc

+// Copyright 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.
+
+#include "components/webdata/common/web_data_service_backend.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "components/webdata/common/web_data_request_manager.h"
+#include "components/webdata/common/web_database.h"
+#include "components/webdata/common/web_database_table.h"
+
+
+using base::Bind;
+using base::FilePath;
+using content::BrowserThread;
+
+WebDataServiceBackend::WebDataServiceBackend(
+    const FilePath& path, Delegate* delegate)
+    : db_path_(path),
+      request_manager_(new WebDataRequestManager()),
+      init_status_(sql::INIT_FAILURE),
+      init_complete_(false),
+      delegate_(delegate) {
+}
+
+void WebDataServiceBackend::AddTable(scoped_ptr<WebDatabaseTable> table) {
+  DCHECK(!db_.get());
+  tables_.push_back(table.release());
+}
+
+void WebDataServiceBackend::InitDatabase() {
+  LoadDatabaseIfNecessary();
+  if (delegate_) {
+    delegate_->DBLoaded(init_status_);
+  }
+}
+
+sql::InitStatus WebDataServiceBackend::LoadDatabaseIfNecessary() {
+  if (init_complete_ || db_path_.empty()) {
+    return init_status_;
+  }
+  init_complete_ = true;
+  db_.reset(new WebDatabase());
+
+  for (ScopedVector<WebDatabaseTable>::iterator it = tables_.begin();
+       it != tables_.end();
+       ++it) {
+    db_->AddTable(*it);
+  }
+
+  init_status_ = db_->Init(db_path_);
+  if (init_status_ != sql::INIT_OK) {
+    LOG(ERROR) << "Cannot initialize the web database: " << init_status_;
+    db_.reset(NULL);
+    return init_status_;
+  }
+
+  db_->BeginTransaction();
+  return init_status_;
+}
+
+void WebDataServiceBackend::ShutdownDatabase(bool should_reinit) {
+  if (db_ && init_status_ == sql::INIT_OK)
+    db_->CommitTransaction();
+  db_.reset(NULL);
+  init_complete_ = !should_reinit; // Setting init_complete_ to true will ensure
+  // that the init sequence is not re-run.
+
+  init_status_ = sql::INIT_FAILURE;
+}
+
+void WebDataServiceBackend::DBWriteTaskWrapper(
+    const WebDatabaseService::WriteTask& task,
+    scoped_ptr<WebDataRequest> request) {
+  LoadDatabaseIfNecessary();
+  if (db_ && init_status_ == sql::INIT_OK && !request->IsCancelled()) {
+    WebDatabase::State state = task.Run(db_.get());
+    if (state == WebDatabase::COMMIT_NEEDED)
+      Commit();
+  }
+  request_manager_->RequestCompleted(request.Pass());
+}
+
+void WebDataServiceBackend::DBReadTaskWrapper(
+    const WebDatabaseService::ReadTask& task,
+    scoped_ptr<WebDataRequest> request) {
+  LoadDatabaseIfNecessary();
+  if (db_ && init_status_ == sql::INIT_OK && !request->IsCancelled()) {
+    request->SetResult(task.Run(db_.get()).Pass());
+  }
+  request_manager_->RequestCompleted(request.Pass());
+}
+
+WebDataServiceBackend::~WebDataServiceBackend() {
+  ShutdownDatabase(false);
+}
+
+void WebDataServiceBackend::Commit() {
+  if (db_ && init_status_ == sql::INIT_OK) {
+    db_->CommitTransaction();
+    db_->BeginTransaction();
+  } else {
+    NOTREACHED() << "Commit scheduled after Shutdown()";
+  }
+}