Second try at splitting WebDataService (minus ownership changes)

chrome/browser/webdata/web_database_service.h

Index: chrome/browser/webdata/web_database_service.h
diff --git a/chrome/browser/webdata/web_database_service.h b/chrome/browser/webdata/web_database_service.h
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+++ b/chrome/browser/webdata/web_database_service.h
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+// 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.
+
+// Chromium settings and storage represent user-selected preferences and
+// information and MUST not be extracted, overwritten or modified except
+// through Chromium defined APIs.
+
+#ifndef CHROME_BROWSER_WEBDATA_WEB_DATABASE_SERVICE_H_
+#define CHROME_BROWSER_WEBDATA_WEB_DATABASE_SERVICE_H_
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/compiler_specific.h"
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/api/webdata/web_data_service_base.h"
+#include "chrome/browser/webdata/web_database.h"
+
+class WebDataServiceBackend;
+class WebDataRequestManager;
+
+namespace content {
+class BrowserContext;
+}
+
+namespace tracked_objects {
+class Location;
+}
+
+class WDTypedResult;
+class WebDataServiceConsumer;
+
+
+////////////////////////////////////////////////////////////////////////////////
+//
+// WebDatabaseService defines the interface to a generic data repository
+// responsible for controlling access to the web database (metadata associated
+// with web pages).
+//
+////////////////////////////////////////////////////////////////////////////////
+
+class WebDatabaseService {
+ public:
+  typedef base::Callback<scoped_ptr<WDTypedResult>(WebDatabase*)> ReadTask;
+  typedef base::Callback<WebDatabase::State(WebDatabase*)> WriteTask;
+  typedef base::Callback<void(sql::InitStatus)> InitCallback;
+
+  // Takes the path to the WebDatabase file.
+  explicit WebDatabaseService(const base::FilePath& path);
+
+  virtual ~WebDatabaseService();
+
+  // Initializes the web database service. Takes a callback which will return
+  // the status of the DB after the init.
+  virtual void LoadDatabase(const InitCallback& callback);
+
+  // Unloads the database without actually shutting down the service.  This can
+  // be used to temporarily reduce the browser process' memory footprint.
+  virtual void UnloadDatabase();
+
+  // Unloads database and will not reload.
+  virtual void ShutdownDatabase();
+
+  // Gets a ptr to the WebDatabase (owned by WebDatabaseService).
+  // TODO(caitkp): remove this method once SyncServices no longer depend on it.
+  virtual WebDatabase* GetDatabaseOnDB() const;
+
+  // Schedule an update/write task on the DB thread.
+  virtual void ScheduleDBTask(
+      const tracked_objects::Location& from_here,
+      const WriteTask& task);
+
+  // Schedule a read task on the DB thread.
+  virtual WebDataServiceBase::Handle ScheduleDBTaskWithResult(
+      const tracked_objects::Location& from_here,
+      const ReadTask& task,
+      WebDataServiceConsumer* consumer);
+
+  // Cancel an existing request for a task on the DB thread.
+  // TODO(caitkp): Think about moving the definition of the Handle type to
+  // somewhere else.
+  virtual void CancelRequest(WebDataServiceBase::Handle h);
+
+ private:
+  base::FilePath path_;
+
+  // The primary owner is |WebDatabaseService| but is refcounted because
+  // PostTask on DB thread may outlive us.
+  scoped_refptr<WebDataServiceBackend> wds_backend_;
+};
+
+#endif  // CHROME_BROWSER_WEBDATA_WEB_DATABASE_SERVICE_H_