[Mac][MC] Add a tooltip for the status item.

chrome/browser/ui/cocoa/notifications/message_center_tray_bridge.mm

 // 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 "chrome/browser/ui/cocoa/notifications/message_center_tray_bridge.h"
 
+#include "base/i18n/number_formatting.h"
 #include "chrome/browser/browser_process.h"
+#include "grit/chromium_strings.h"
+#include "grit/ui_strings.h"
+#include "ui/base/l10n/l10n_util.h"
+#import "ui/base/l10n/l10n_util_mac.h"
 #import "ui/message_center/cocoa/popup_collection.h"
 #import "ui/message_center/cocoa/status_item_view.h"
 #import "ui/message_center/cocoa/tray_controller.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/message_center_tray.h"
 
 namespace message_center {
 
 MessageCenterTrayDelegate* CreateMessageCenterTray() {
   return new MessageCenterTrayBridge(g_browser_process->message_center());
@@ skipping 17 matching lines @@
         tray_->HideMessageCenterBubble();
       else
         tray_->ShowMessageCenterBubble();
   }];
 }
 
 MessageCenterTrayBridge::~MessageCenterTrayBridge() {
 }
 
 void MessageCenterTrayBridge::OnMessageCenterTrayChanged() {
-  [status_item_view_ setUnreadCount:
-      message_center_->UnreadNotificationCount()];
+  size_t unread_count = message_center_->UnreadNotificationCount();
+  [status_item_view_ setUnreadCount:unread_count];
+
+  string16 product_name = l10n_util::GetStringUTF16(IDS_SHORT_PRODUCT_NAME);
+  if (unread_count > 0) {
+    string16 unread_count_string = base::FormatNumber(unread_count);
+    [status_item_view_ setToolTip:
+        l10n_util::GetNSStringF(IDS_MESSAGE_CENTER_TOOLTIP_UNREAD,
+            product_name, unread_count_string)];
+  } else {
+    [status_item_view_ setToolTip:
+        l10n_util::GetNSStringF(IDS_MESSAGE_CENTER_TOOLTIP, product_name)];
+  }
+
   [tray_controller_ onMessageCenterTrayChanged];
 }
 
 bool MessageCenterTrayBridge::ShowPopups() {
   popup_collection_.reset(
       [[MCPopupCollection alloc] initWithMessageCenter:message_center_]);
   return true;
 }
 
 void MessageCenterTrayBridge::HidePopups() {
   popup_collection_.reset();
 }
 
 void MessageCenterTrayBridge::UpdatePopups() {
   // Nothing to do since the popup collection observes the MessageCenter
   // directly.
 }
 
 bool MessageCenterTrayBridge::ShowMessageCenter() {
   [status_item_view_ setHighlight:YES];
   NSRect frame = [[status_item_view_ window] frame];
   [tray_controller_ showTrayAt:NSMakePoint(NSMinX(frame), NSMinY(frame))];
   return true;
 }
 
 void MessageCenterTrayBridge::HideMessageCenter() {
   [status_item_view_ setHighlight:NO];
   [tray_controller_ close];
 }