Add NetworkNotificationView to tray_network.

ash/system/tray/system_tray_bubble.h

Index: ash/system/tray/system_tray_bubble.h
diff --git a/ash/system/tray/system_tray_bubble.h b/ash/system/tray/system_tray_bubble.h
index 90804c62583c7bb96840c46038ab8ebd8e495bfd..d26c592249558a1b2a21dbbee02fc52824074b8d 100644
--- a/ash/system/tray/system_tray_bubble.h
+++ b/ash/system/tray/system_tray_bubble.h
@@ -54,8 +54,11 @@ class SystemTrayBubbleView : public views::BubbleDelegateView {
   virtual void OnMouseEntered(const views::MouseEvent& event) OVERRIDE;
   virtual void OnMouseExited(const views::MouseEvent& event) OVERRIDE;
 
+  void set_max_height(int height) { max_height_ = height; }
+
   SystemTrayBubble* host_;
   bool can_activate_;
+  int max_height_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTrayBubbleView);
 };
@@ -82,6 +85,7 @@ class SystemTrayBubble : public base::MessagePumpObserver,
     bool can_activate;
     ash::user::LoginStatus login_status;
     int arrow_offset;
+    int max_height;
   };
 
   SystemTrayBubble(ash::SystemTray* tray,