Plumb NotifierId to status icon balloons

chrome/browser/status_icons/status_icon.h

 // Copyright (c) 2012 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 CHROME_BROWSER_STATUS_ICONS_STATUS_ICON_H_
 #define CHROME_BROWSER_STATUS_ICONS_STATUS_ICON_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "chrome/browser/status_icons/status_icon_menu_model.h"
 
 namespace gfx {
 class ImageSkia;
 }
 
+namespace message_center {
+struct NotifierId;
+}
+
 class StatusIconObserver;
 
 class StatusIcon {
  public:
   StatusIcon();
   virtual ~StatusIcon();
 
   // Sets the image associated with this status icon.
   virtual void SetImage(const gfx::ImageSkia& image) = 0;
 
   // Sets the hover text for this status icon. This is also used as the label
   // for the menu item which is created as a replacement for the status icon
   // click action on platforms that do not support custom click actions for the
   // status icon (e.g. Ubuntu Unity).
   virtual void SetToolTip(const base::string16& tool_tip) = 0;
 
   // Displays a notification balloon with the specified contents.
   // Depending on the platform it might not appear by the icon tray.
-  virtual void DisplayBalloon(const gfx::ImageSkia& icon,
-                              const base::string16& title,
-                              const base::string16& contents) = 0;
+  virtual void DisplayBalloon(
+      const gfx::ImageSkia& icon,
+      const base::string16& title,
+      const base::string16& contents,
+      const message_center::NotifierId& notifier_id) = 0;

[Peter Beverloo, 2015/10/10 16:35:27]

I'm a bit torn on what type to use here.

Yes, mc::NotifierId certainly is applicable since that's what it will be used
as, but it's entirely unrelated to what any platform-native (e.g. Windows)
implementation would be using, unless you think of it strictly as a data
carrier.

On the other end, using something like "const char* source" is not super obvious
either, and would require one to read this comment (when amended) for context.

I don't feel strongly one way or another, but perhaps Justin or Andrew will have
an opinion.

[johnme, 2015/10/12 14:34:09]

Since this is a method for displaying "a notification balloon", it doesn't seem
unreasonable for it to always take a NotifierId, even on platforms where it uses
a native balloon rather than Chrome's notifications.

 
   // Set the context menu for this icon. The icon takes ownership of the passed
   // context menu. Passing NULL results in no menu at all.
   void SetContextMenu(scoped_ptr<StatusIconMenuModel> menu);
 
   // Adds/Removes an observer for clicks on the status icon. If an observer is
   // registered, then left clicks on the status icon will result in the observer
   // being called, otherwise, both left and right clicks will display the
   // context menu (if any).
   void AddObserver(StatusIconObserver* observer);
@@ skipping 24 matching lines @@
  private:
   base::ObserverList<StatusIconObserver> observers_;
 
   // Context menu, if any.
   scoped_ptr<StatusIconMenuModel> context_menu_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusIcon);
 };
 
 #endif  // CHROME_BROWSER_STATUS_ICONS_STATUS_ICON_H_