DPWA: Clean up unused callback for Run on OS Login in WebAppInstallTask

The callback WebAppInstallTask::OnRegisteredRunOnOsLogin() is no longer
used now that the call to OS hooks, Run on OS Login included, has been
refactored into OsIntegrationManager class.
(See https://crrev.com/c/2272120)

This CL is to clean up this no-longer-needed method.

Bug: 1114220
Change-Id: Ib3a3b7adc4bc330144489c02a598ab6e18a0a6ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342992Reviewed-by: Alexey Baskakov <loyso@chromium.org>
Commit-Queue: Carlos Frias <carlos.frias@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#796700}

chrome/browser/web_applications/web_app_install_task.cc

@@ -804,10 +804,4 @@ void WebAppInstallTask::OnOsHooksCreated(
   CallInstallCallback(app_id, InstallResultCode::kSuccessNewInstall);
 }
 
-void WebAppInstallTask::OnRegisteredRunOnOsLogin(
-    const AppId& app_id,
-    bool registered_run_on_os_login) {
-  CallInstallCallback(app_id, InstallResultCode::kSuccessNewInstall);
-}
-
 }  // namespace web_app

chrome/browser/web_applications/web_app_install_task.h

@@ -229,8 +229,6 @@ class WebAppInstallTask : content::WebContentsObserver {
   void OnOsHooksCreated(bool open_as_window,
                         const AppId& app_id,
                         const OsHooksResults os_hooks_results);
-  void OnRegisteredRunOnOsLogin(const AppId& app_id,
-                                bool registered_run_on_os_login);
 
   // Whether we should just obtain WebApplicationInfo instead of the actual
   // installation.