Replace WebDatabaseObserver with callbacks

components/webdata/common/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 COMPONENTS_WEBDATA_COMMON_WEB_DATA_SERVICE_BASE_H_
 #define COMPONENTS_WEBDATA_COMMON_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 "components/webdata/common/web_database_observer.h"
 #include "components/webdata/common/webdata_export.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_source.h"
 #include "sql/init_status.h"
 
 class WebDatabase;
 class WebDatabaseService;
 class WebDatabaseTable;
 
 namespace base {
 class Thread;
 }
 
 // Base for WebDataService class hierarchy.
 class WEBDATA_EXPORT WebDataServiceBase
-    : public WebDatabaseObserver,
-      public base::RefCountedThreadSafe<WebDataServiceBase,
+    : public base::RefCountedThreadSafe<WebDataServiceBase,
           content::BrowserThread::DeleteOnUIThread> {
  public:
   // All requests return an opaque handle of the following type.
   typedef int Handle;
 
   // 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.
   //
   // The ownership of |wdbs| is shared, with the primary owner being the
   // WebDataServiceWrapper, and secondary owners being subclasses of
   // WebDataServiceBase, which receive |wdbs| upon construction. The
   // WebDataServiceWrapper handles the initializing and shutting down and of
   // the |wdbs| object.
   WebDataServiceBase(scoped_refptr<WebDatabaseService> wdbs,
                      const ProfileErrorCallback& callback);
 
-  // WebDatabaseObserver implementation.
-  virtual void WebDatabaseLoaded() OVERRIDE;
-  virtual void WebDatabaseLoadFailed(sql::InitStatus status) OVERRIDE;
-
   // Cancel any pending request. You need to call this method if your
   // WebDataServiceConsumer is about to be deleted.
   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();
 
   // 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();
 
   // 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();
 
-  virtual void AddDBObserver(WebDatabaseObserver* observer);
-  virtual void RemoveDBObserver(WebDatabaseObserver* observer);
+  // Register a callback to be notified that the database has loaded. Multiple
+  // callbacks may be registered, and each will be called at most once
+  // (following a successful database load), then cleared.
+  // Note: if the database load is already complete, then the callback will NOT
+  // be stored or called.
+  virtual void RegisterDBLoadedCallback(
+      const base::Callback<void(void)>& callback);
 
   // 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_refptr<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>;
   // We have to friend RCTS<> so WIN shared-lib build is happy (crbug/112250).
   friend class base::RefCountedThreadSafe<WebDataServiceBase,
       content::BrowserThread::DeleteOnUIThread>;
 
   ProfileErrorCallback profile_error_callback_;
 };
 
 #endif  // COMPONENTS_WEBDATA_COMMON_WEB_DATA_SERVICE_BASE_H_