Implement message center on Windows

ui/message_center/message_center_tray.h

+// Copyright (c) 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.
+
+#ifndef UI_MESSAGE_CENTER_MESSAGE_CENTER_TRAY_H_
+#define UI_MESSAGE_CENTER_MESSAGE_CENTER_TRAY_H_
+
+#include "base/observer_list.h"
+#include "ui/message_center/message_center.h"
+#include "ui/message_center/message_center_export.h"
+#include "ui/views/bubble/tray_bubble_view.h"
+
+namespace message_center {
+class MessageBubbleBase;
+class MessagePopupBubble;
+class QuietModeBubble;
+}
+
+namespace views {
+class Widget;
+}
+
+namespace ui {
+

[Pete Williamson, 2013/01/24 19:41:59]

Put MessageCenterTrayDelegate into its own .h file, since it is used in more
places than just this file.
Also, let's add any useful comments that we can on each method.  Since this is
an interface, implementors will come here to see how to implement the interface.

[dewittj, 2013/01/25 00:49:04]

Done.

+class MessageCenterTrayDelegate {
+ public:
+  static MessageCenterTrayDelegate* CreateForPlatform();
+  virtual ~MessageCenterTrayDelegate() {};
+
+  virtual void OnMessageCenterTrayChanged() = 0;
+  virtual bool ShowPopups(message_center::MessageBubbleBase* bubble) = 0;
+  virtual void HidePopups() = 0;
+  virtual void UpdatePopups() = 0;
+  virtual bool ShowMessageCenter(message_center::MessageBubbleBase* bubble) = 0;
+  virtual void HideMessageCenter() = 0;
+  virtual void UpdateMessageCenter() = 0;
+};
+
+// Class that observes a MessageCenter.  Manages the popup and message center
+// bubbles.  Tells the MessageCenterTrayHost when the tray is changed, as well
+// as when bubbles are shown and hidden.
+class MESSAGE_CENTER_EXPORT MessageCenterTray
+    : public message_center::MessageCenter::Observer {
+ public:
+  MessageCenterTray(MessageCenterTrayDelegate* delegate,
+                    message_center::MessageCenter* message_center);
+  virtual ~MessageCenterTray();
+
+  // Shows or updates the message center bubble and hides the popup bubble.
+  void ShowMessageCenterBubble();
+
+  // Returns whether the message center was visible before.
+  bool HideMessageCenterBubble();
+
+  void ToggleMessageCenterBubble();
+
+  // Causes an update if the popup bubble is already shown.
+  void ShowPopupBubble();
+
+  // Returns whether the popup was visible before.
+  bool HidePopupBubble();
+
+  bool message_center_visible() { return message_center_visible_; }
+  bool popups_visible() { return popups_visible_; }
+  MessageCenterTrayDelegate* delegate() { return delegate_; }
+  message_center::MessageCenter* message_center() { return message_center_; }
+
+  // Overridden from message_center::MessageCenter::Observer.
+  virtual void OnMessageCenterChanged(bool new_notification) OVERRIDE;
+
+ private:
+  void NotifyMessageCenterTrayChanged();
+

[Pete Williamson, 2013/01/24 19:41:59]

Let's add comments about ownership of the message center and delegate pointers. 
It seems that this class expects them to be valid for the entire lifetime of the
class, and for the code that creates this class to enforce that constraint and
manage the lifetimes of the delegate and message center, is that right? 

[dewittj, 2013/01/25 00:49:04]

Done.

+  message_center::MessageCenter* message_center_;
+  bool message_center_visible_;
+  bool popups_visible_;
+  MessageCenterTrayDelegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessageCenterTray);
+};
+
+}  // namespace ui
+
+#endif  // UI_MESSAGE_CENTER_MESSAGE_CENTER_TRAY_H_