Create a common base class for all the webdatas

chrome/browser/api/webdata/web_data_service_base.h

 // 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.
 
 #ifndef CHROME_BROWSER_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_
 #define CHROME_BROWSER_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_
 
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_source.h"
+#include "sql/init_status.h"
+
+class WebDatabase;
+class WebDatabaseService;
+
+namespace base {
+class Thread;
+}
 
 // Base for WebDataService class hierarchy.
-class WebDataServiceBase {
+class WebDataServiceBase
+    : public base::RefCountedThreadSafe<WebDataServiceBase,
+          content::BrowserThread::DeleteOnUIThread> {
  public:
   // All requests return an opaque handle of the following type.
   typedef int Handle;
 
-  virtual ~WebDataServiceBase() {}
+  WebDataServiceBase();
 
   // Cancel any pending request. You need to call this method if your
   // WebDataServiceConsumer is about to be deleted.
-  virtual void CancelRequest(Handle h) = 0;
+  virtual void CancelRequest(Handle h);
 
   // Returns the notification source for this service. This may use a
   // pointer other than this object's |this| pointer.
-  virtual content::NotificationSource GetNotificationSource() = 0;
+  virtual content::NotificationSource GetNotificationSource();
+
+  // Shutdown the web data service. The service can no longer be used after this
+  // call.
+  virtual void ShutdownOnUIThread();
+
+  // Initializes the web data service.
+  virtual void Init(const base::FilePath& path);
+
+  // Unloads the database without actually shutting down the service.  This can
+  // be used to temporarily reduce the browser process' memory footprint.
+  void UnloadDatabase();
+
+  // Unloads the database permanently and shuts down service.
+  void ShutdownDatabase();
+
+  // Returns true if the database load has completetd successfully, and
+  // ShutdownOnUIThread has not yet been called.
+  virtual bool IsDatabaseLoaded();
+
+  // Returns a pointer to the DB (used by SyncableServices). May return NULL if
+  // the database is not loaded or otherwise unavailable. Must be called on
+  // DBThread.
+  virtual WebDatabase* GetDatabase();
+
+ protected:
+  virtual ~WebDataServiceBase();
+
+  // Our database service.
+  scoped_ptr<WebDatabaseService> wdbs_;
+
+  // True if we've received a notification that the WebDatabase has loaded.
+  bool db_loaded_;
+
+ private:
+  friend struct content::BrowserThread::DeleteOnThread<
+      content::BrowserThread::UI>;
+  friend class base::DeleteHelper<WebDataServiceBase>;
+
+  void DBInitFailed(sql::InitStatus sql_status);
+  void NotifyDatabaseLoadedOnUIThread();
+  void DatabaseInitOnDB(sql::InitStatus status);
 };
 
 #endif  // CHROME_BROWSER_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_