Implement notifications for the DisplayBalloon method on Linux and Mac.

chrome/browser/ui/cocoa/status_icons/status_icon_mac.mm

 // Copyright (c) 2011 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/status_icons/status_icon_mac.h"
 
 #include "base/logging.h"
 #include "base/sys_string_conversions.h"
 #include "skia/ext/skia_utils_mac.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ skipping 61 matching lines @@
   }
 }
 
 void StatusIconMac::SetToolTip(const string16& tool_tip) {
   [item() setToolTip:base::SysUTF16ToNSString(tool_tip)];
 }
 
 void StatusIconMac::DisplayBalloon(const SkBitmap& icon,
                                    const string16& title,
                                    const string16& contents) {
-  // TODO(atwilson): Figure out the right UI to display here when actually
-  // needed (not yet called).
-  // http://crbug.com/74970
+  notification_.DisplayBalloon(icon, title, contents);
 }
 
 void StatusIconMac::UpdatePlatformContextMenu(ui::MenuModel* menu) {
   // TODO(atwilson): Add support for context menus for Mac when actually needed
   // (not yet used by anything) - http://crbug.com/37375.
 }