Make Task Manager sort more meaningful

chrome/browser/task_management/providers/web_contents/subframe_task.h

 // Copyright 2015 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_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_SUBFRAME_TASK_H_
 #define CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_SUBFRAME_TASK_H_
 
 #include "base/macros.h"
 #include "chrome/browser/task_management/providers/web_contents/renderer_task.h"
 
@@ skipping 11 matching lines @@
   SubframeTask(content::RenderFrameHost* render_frame_host,
                content::WebContents* web_contents,
                RendererTask* main_task);
   ~SubframeTask() override;
 
   // task_management::RendererTask:
   void UpdateTitle() override;
   void UpdateFavicon() override;
   void Activate() override;
 
+  // task_management::Task:
+  Task* GetParentTask() const override;
+
  private:
   // The task for the main frame of this WebContents.
   RendererTask* main_task_;
   DISALLOW_COPY_AND_ASSIGN(SubframeTask);
 };
 
 }  // namespace task_management
 
 
 #endif  // CHROME_BROWSER_TASK_MANAGEMENT_PROVIDERS_WEB_CONTENTS_SUBFRAME_TASK_H_