Teach the PlatformNotificationContext how to delete notifications.

content/browser/notifications/platform_notification_context.h

 // Copyright 2015 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 CONTENT_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_CONTEXT_H_
 #define CONTENT_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_CONTEXT_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 25 matching lines @@
   explicit PlatformNotificationContext(const base::FilePath& path);
 
   using ReadResultCallback =
       base::Callback<void(bool /* success */,
                           const NotificationDatabaseData&)>;
 
   using WriteResultCallback =
       base::Callback<void(bool /* success */,
                           int64_t /* notification_id */)>;
 
+  using DeleteResultCallback = base::Callback<void(bool /* success */)>;
+
   // Reads the data associated with |notification_id| belonging to |origin|
   // from the database. |callback| will be invoked with the success status
   // and a reference to the notification database data when completed.
   void ReadNotificationData(int64_t notification_id,
                             const GURL& origin,
                             const ReadResultCallback& callback);
 
   // Writes the data associated with a notification to a database. When this
   // action completed, |callback| will be invoked with the success status and
   // the persistent notification id when written successfully.
   void WriteNotificationData(const GURL& origin,
                              const NotificationDatabaseData& database_data,
                              const WriteResultCallback& callback);
 
+  // Deletes all data associated with |notification_id| belonging to |origin|
+  // from the database. |callback| will be invoked with the success status
+  // when the operation has completed.
+  void DeleteNotificationData(int64_t notification_id,
+                              const GURL& origin,
+                              const DeleteResultCallback& callback);
+
  private:
   friend class base::RefCountedThreadSafe<PlatformNotificationContext>;
   friend class PlatformNotificationContextTest;
 
   virtual ~PlatformNotificationContext();
 
   // Initializes the database if neccesary. Must be called on the IO thread.
   // |success_closure| will be invoked on a the |task_runner_| thread when
   // everything is available, or |failure_closure_| will be invoked on the
   // IO thread when initialization fails.
   void LazyInitialize(const base::Closure& success_closure,
                       const base::Closure& failure_closure);
 
   // Opens the database. Must be called on the |task_runner_| thread. When the
   // database has been opened, |success_closure| will be invoked on the task
   // thread, otherwise |failure_closure_ will be invoked on the IO thread.
   void OpenDatabase(const base::Closure& success_closure,
                     const base::Closure& failure_closure);
 
   // Actually reads the notification data from the database. Must only be
-  // called on the |task_runner_| thread. Will post a task to |callback| on
-  // the IO thread when the operation has completed.
+  // called on the |task_runner_| thread. Will post a task to the IO thread
+  // for invoking |callback| on when the operation has completed.

[johnme, 2015/03/16 16:55:18]

Nit: While you're re-wording this, why not just "Will invoke |callback| on the
IO thread when"?

[Peter Beverloo, 2015/03/16 18:16:51]

Because it won't invoke, it'll post a task to invoke. The former sounds to me
like it may be synchronous?

[johnme, 2015/03/16 19:34:46]

Fair. Maybe say "|callback| will be invoked on the IO threads when" then, like
you do above.

   void DoReadNotificationData(int64_t notification_id,
                               const GURL& origin,
                               const ReadResultCallback& callback);
 
   // Actually writes the notification database to the database. Must only be
-  // called on the |task_runner_| thread. Will post a task to |callback| on
-  // the IO thread when the operation has completed.
+  // called on the |task_runner_| thread. Will post a task to the IO thread
+  // for invoking |callback| on when the operation has completed.
   void DoWriteNotificationData(const GURL& origin,
                                const NotificationDatabaseData& database_data,
                                const WriteResultCallback& callback);
 
+  // Actually deletes the notification information from the database. Must only
+  // be called on the |task_runner_| thread. Will post a task to the IO thread
+  // for invoking |callback| on when the operation has completed.
+  void DoDeleteNotificationData(int64_t notification_id,
+                                const GURL& origin,
+                                const DeleteResultCallback& callback);
+
   // Returns the path in which the database should be initialized. May be empty.
   base::FilePath GetDatabasePath() const;
 
   // Sets the task runner to use for testing purposes.
   void SetTaskRunnerForTesting(
       const scoped_refptr<base::SequencedTaskRunner>& task_runner);
 
   base::FilePath path_;
 
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
   scoped_ptr<NotificationDatabase> database_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformNotificationContext);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_CONTEXT_H_