Implement a poor man's PostAfterStartupTask() function.

content/public/browser/content_browser_client.cc

 // 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.
 
 #include "content/public/browser/content_browser_client.h"
 
 #include "base/files/file_path.h"
 #include "content/public/browser/client_certificate_delegate.h"
 #include "ui/gfx/image/image_skia.h"
 #include "url/gurl.h"
 
 namespace content {
 
 BrowserMainParts* ContentBrowserClient::CreateBrowserMainParts(
     const MainFunctionParams& parameters) {
   return nullptr;
 }
 
+void ContentBrowserClient::PostAfterStartupTask(
+    const tracked_objects::Location& from_here,
+    const scoped_refptr<base::TaskRunner>& task_runner,
+    const base::Closure& task) {
+  task_runner->PostTask(from_here, task);
+}
+
 WebContentsViewDelegate* ContentBrowserClient::GetWebContentsViewDelegate(
     WebContents* web_contents) {
   return nullptr;
 }
 
 GURL ContentBrowserClient::GetEffectiveURL(BrowserContext* browser_context,
                                            const GURL& url) {
   return url;
 }
 
@@ skipping 308 matching lines @@
 
 #if defined(VIDEO_HOLE)
 ExternalVideoSurfaceContainer*
 ContentBrowserClient::OverrideCreateExternalVideoSurfaceContainer(
     WebContents* web_contents) {
   return nullptr;
 }
 #endif
 
 }  // namespace content