mash: Update shelf pin prefs in ShelfModelObserver overrides.

chrome/browser/ui/ash/launcher/launcher_arc_app_updater.cc

 // Copyright 2016 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/ash/launcher/launcher_arc_app_updater.h"
 
 LauncherArcAppUpdater::LauncherArcAppUpdater(
     Delegate* delegate,
     content::BrowserContext* browser_context)
     : LauncherAppUpdater(delegate, browser_context) {
   ArcAppListPrefs* prefs = ArcAppListPrefs::Get(browser_context);
   DCHECK(prefs);
   prefs->AddObserver(this);
 }
 
 LauncherArcAppUpdater::~LauncherArcAppUpdater() {
   ArcAppListPrefs* prefs = ArcAppListPrefs::Get(browser_context());
   DCHECK(prefs);
   prefs->RemoveObserver(this);
 }
 
 void LauncherArcAppUpdater::OnAppRegistered(
     const std::string& app_id,
     const ArcAppListPrefs::AppInfo& app_info) {
   delegate()->OnAppInstalled(browser_context(), app_id);
 }
 
 void LauncherArcAppUpdater::OnAppRemoved(const std::string& app_id) {
+  // When disabling ARC, apps are removed, but sync items should not be deleted.

[James Cook, 2017/03/29 14:28:02]

I suggest explaining why the items should not be deleted, like it your CL
comments.

[msw, 2017/03/29 21:34:17]

Done.

+  // Notify the delegate that the app is being disabled, and shelf item removal
+  // should not trigger pin position removal from the sync model. When app
+  // removal should be synced, AppListModelBuilder::RemoveApp will call
+  // AppListSyncableService::RemoveUninstalledItem and trigger RemoveSyncItem.
+  delegate()->OnAppDisabling(app_id);
   delegate()->OnAppUninstalledPrepared(browser_context(), app_id);
   delegate()->OnAppUninstalled(browser_context(), app_id);
+  delegate()->OnAppDisabled(app_id);

[James Cook, 2017/03/29 14:28:03]

It seems like these OnAppDisabling() etc. functions should also be called from
LauncherExtensionAppUpdater, or these shouldn't be delegate methods and
LauncherArcAppUpdater should be calling directly into CLC.

[msw, 2017/03/29 21:34:17]

Good call! Changed this to directly call into ChromeLauncherController.

 }