wd5-syncableServices for try only

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/callback_forward.h"
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/supports_user_data.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() {}
+  // Users of this class may provide a callback to handle errors
+  // (e.g. by showing a UI). The callback is called only on error, and
+  // takes a single parameter, the sql::InitStatus value from trying
+  // to open the database.
+  // TODO(joi): Should we combine this with WebDatabaseService::InitCallback?
+  typedef base::Callback<void(sql::InitStatus)> ProfileErrorCallback;
+
+  // |callback| will only be invoked on error, and only if
+  // |callback.is_null()| evaluates to false.
+  explicit WebDataServiceBase(const ProfileErrorCallback& callback);
 
   // 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();
+
+  // Returns a SupportsUserData objects that may be used to store data
+  // owned by the DB thread on this object. Should be called only from
+  // the DB thread, and will be destroyed on the DB thread soon after
+  // |ShutdownOnUIThread()| is called.
+  base::SupportsUserData* GetDBUserData();
+
+ protected:
+  virtual ~WebDataServiceBase();
+  virtual void ShutdownOnDBThread();
+
+  // 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>;
+
+  ProfileErrorCallback profile_error_callback_;
+
+  // This makes the destructor public, and thus allows us to aggregate
+  // SupportsUserData. It is private by default to prevent incorrect
+  // usage in class hierarchies where it is inherited by
+  // reference-counted objects.
+  class SupportsUserDataAggregatable : public base::SupportsUserData {
+   public:
+    SupportsUserDataAggregatable() {}
+    virtual ~SupportsUserDataAggregatable() {}
+   private:
+    DISALLOW_COPY_AND_ASSIGN(SupportsUserDataAggregatable);
+  };
+
+  // Storage for user data to be accessed only on the DB thread. May
+  // be used e.g. for SyncableService subclasses that need to be owned
+  // by this object. Is created on first call to |GetDBUserData()|.
+  scoped_ptr<SupportsUserDataAggregatable> db_thread_user_data_;
+
+  void DBInitFailed(sql::InitStatus sql_status);
+  void NotifyDatabaseLoadedOnUIThread();
+  void DatabaseInitOnDB(sql::InitStatus status);
 };
 
 #endif  // CHROME_BROWSER_API_WEBDATA_WEB_DATA_SERVICE_BASE_H_