mash: Update shelf pin prefs in ShelfModelObserver overrides.

chrome/browser/ui/ash/launcher/launcher_app_updater.h

Index: chrome/browser/ui/ash/launcher/launcher_app_updater.h
diff --git a/chrome/browser/ui/ash/launcher/launcher_app_updater.h b/chrome/browser/ui/ash/launcher/launcher_app_updater.h
index fb383e63cef060832383e579ae03e362ffa68d07..c0800c8230619962d37054c82476ec6a15c172a0 100644
--- a/chrome/browser/ui/ash/launcher/launcher_app_updater.h
+++ b/chrome/browser/ui/ash/launcher/launcher_app_updater.h
@@ -28,6 +28,11 @@ class LauncherAppUpdater {
     virtual void OnAppUninstalled(content::BrowserContext* browser_context,
                                   const std::string& app_id) {}
 
+    // This pair of functions is called before and after disabling an app. This
+    // prevents shelf item removal from triggering a sync model pref update.
+    virtual void OnAppDisabling(const std::string& app_id) {}
+    virtual void OnAppDisabled(const std::string& app_id) {}
+
    protected:
     virtual ~Delegate() {}
   };