Implement message center on Windows

ui/message_center/message_center_tray.cc

Index: ui/message_center/message_center_tray.cc
diff --git a/ui/message_center/message_center_tray.cc b/ui/message_center/message_center_tray.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a739ccc322d1204afc3f699fcb60d2b9266a1151
--- /dev/null
+++ b/ui/message_center/message_center_tray.cc
@@ -0,0 +1,110 @@
+// 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.
+
+#include "ui/message_center/message_center_tray.h"
+
+#include "base/observer_list.h"
+#include "base/utf_string_conversions.h"
+#include "ui/message_center/message_center_tray_delegate.h"
+
+namespace message_center {
+
+MessageCenterTray::MessageCenterTray(
+    MessageCenterTrayDelegate* delegate,
+    message_center::MessageCenter* message_center)
+    : message_center_(message_center),
+      message_center_visible_(false),
+      popups_visible_(false),
+      delegate_(delegate) {
+  message_center_->AddObserver(this);
+}
+
+MessageCenterTray::~MessageCenterTray() {
+  message_center_->RemoveObserver(this);
+}
+
+void MessageCenterTray::ShowMessageCenterBubble() {

[miket_OOO, 2013/01/25 17:14:48]

This isn't a big deal, but I wonder why only hide returns the boolean indicating
whether the state changed. I'm sure the answer is because nobody cares about
show, but the asymmetry is notable.

[dewittj, 2013/01/25 19:38:46]

Hm, maybe it would be useful to return the answer in tests.  Good comment.

+  if (message_center_visible_)
+    return;
+
+  message_center_->SetMessageCenterVisible(true);
+  HidePopupBubble();
+
+  message_center_visible_ = delegate_->ShowMessageCenter();

[miket_OOO, 2013/01/25 17:14:48]

Is there any chance this could fail? Could message_center_'s idea of visibility
and message_center_visible_ get out of sync?

[dewittj, 2013/01/25 19:38:46]

I suppose there is a chance.  It can fail when the screen is locked on ChromeOS,
for example.

Fixed.

+}
+
+bool MessageCenterTray::HideMessageCenterBubble() {
+  if (!message_center_visible_)
+    return false;
+  delegate_->HideMessageCenter();
+  message_center_visible_ = false;
+  message_center_->SetMessageCenterVisible(false);
+  NotifyMessageCenterTrayChanged();
+  return true;
+}
+
+void MessageCenterTray::ToggleMessageCenterBubble() {
+  if (message_center_visible_)
+    HideMessageCenterBubble();
+  else
+    ShowMessageCenterBubble();
+}
+
+void MessageCenterTray::ShowPopupBubble() {
+  if (message_center_visible_) {
+    // We don't want to show popups if the user is already looking at the
+    // message center.  Instead, update it.
+    delegate_->UpdateMessageCenter();
+    return;
+  }
+
+  if (popups_visible_) {
+    delegate_->UpdatePopups();
+    NotifyMessageCenterTrayChanged();
+    return;
+  }
+
+  if (!message_center_->HasPopupNotifications())
+    return;
+
+  popups_visible_ = delegate_->ShowPopups();
+  NotifyMessageCenterTrayChanged();
+}
+
+bool MessageCenterTray::HidePopupBubble() {
+  if (!popups_visible_)
+    return false;
+
+  delegate_->HidePopups();
+  popups_visible_ = false;
+  NotifyMessageCenterTrayChanged();
+
+  return true;
+}
+
+void MessageCenterTray::OnMessageCenterChanged(bool new_notification) {
+  if (message_center_visible_) {
+    if (message_center_->NotificationCount() == 0)
+      HideMessageCenterBubble();
+    else
+      delegate_->UpdateMessageCenter();
+  }
+  if (popups_visible_) {
+    if (message_center_->NotificationCount() == 0)
+      HidePopupBubble();
+    else
+      delegate_->UpdatePopups();
+  }
+
+  if (new_notification)
+    ShowPopupBubble();
+
+  NotifyMessageCenterTrayChanged();
+}
+
+void MessageCenterTray::NotifyMessageCenterTrayChanged() {
+  delegate_->OnMessageCenterTrayChanged();
+}
+
+}  // namespace message_center