Implement message center on Windows

ui/message_center/message_center_tray_delegate.h

Index: ui/message_center/message_center_tray_delegate.h
diff --git a/ui/message_center/message_center_tray_delegate.h b/ui/message_center/message_center_tray_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..edd31a3f0ebf7efac40e74dcbb2d38cf90b0c841
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+++ b/ui/message_center/message_center_tray_delegate.h
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+// 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_DELEGATE_H_
+#define UI_MESSAGE_CENTER_MESSAGE_CENTER_TRAY_DELEGATE_H_
+
+namespace message_center {
+
+// A MessageCenterTrayDelegate class is responsible for managing the various UI
+// surfaces that should be displayed when the MessageCenter is changed.
+class MESSAGE_CENTER_EXPORT MessageCenterTrayDelegate {
+ public:
+  virtual ~MessageCenterTrayDelegate() {};
+
+  // Called whenever a change to the visible UI has occurred.
+  virtual void OnMessageCenterTrayChanged() = 0;
+
+  // Display the popup bubbles for new notifications to the user.  Returns true
+  // if popups were actually displayed to the user.
+  virtual bool ShowPopups() = 0;
+
+  // Remove the popup bubbles from the UI.
+  virtual void HidePopups() = 0;
+
+  // Called when a change to the message center could cause a change to popups
+  // that are currently being displayed.
+  virtual void UpdatePopups() = 0;
+
+  // Display the message center containing all undismissed notifications to the
+  // user.  Returns true if the center was actually displayed to the user.
+  virtual bool ShowMessageCenter() = 0;
+
+  // Remove the message center from the UI.
+  virtual void HideMessageCenter() = 0;
+
+  // Called when a change to the message center could cause a change to the
+  // message center widget that is currently being displayed.
+  virtual void UpdateMessageCenter() = 0;
+};
+
+}  // namespace message_center
+
+#endif  // UI_MESSAGE_CENTER_MESSAGE_CENTER_TRAY_DELEGATE_H_