Task Manager: Make double-clicking on an extension do something useful.

chrome/browser/task_management/providers/web_contents/web_contents_task_provider.cc

 // 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.
 
 #include "chrome/browser/task_management/providers/web_contents/web_contents_task_provider.h"
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/stl_util.h"
 #include "chrome/browser/task_management/providers/web_contents/subframe_task.h"
@@ skipping 212 matching lines @@
   RendererTask* new_task = nullptr;
   // We don't create a task if there's one for this site_instance AND
   // if this is not the main frame or we did record a main frame for the entry.
   if (!site_instance_exists || (is_main_frame && !site_instance_is_main)) {
     if (is_main_frame) {
       const WebContentsTag* tag =
           WebContentsTag::FromWebContents(web_contents());
       new_task = tag->CreateTask();
       main_frame_site_instance_ = site_instance;
     } else {
-      new_task = new SubframeTask(render_frame_host, web_contents());
+      new_task =
+          new SubframeTask(render_frame_host, web_contents(),
+                           GetTaskForFrame(web_contents()->GetMainFrame()));

[afakhry, 2016/05/25 20:07:09]

I hope the task of the main frame gets created before its subframe tasks. Is
that guaranteed?

[ncarter (slow), 2016/05/25 20:34:23]

Yes; the way we use WebContentsObserver guarantees this (in general, creation
and ForEachFrame guarantee top-down, and deletion is guaranteed to be
bottom-up.) WebContentsObserverSanityChecker enforces these assumptions.

     }
   }
 
   if (site_instance_exists) {
     // One of the existing frame hosts for this site instance.
     FramesList& existing_frames_for_site_instance =
         frames_by_site_instance_[site_instance];
     RenderFrameHost* existing_rfh = existing_frames_for_site_instance[0];
     RendererTask* old_task = tasks_by_frames_[existing_rfh];
 
@@ skipping 148 matching lines @@
 
   WebContentsEntry* entry = itr->second;
   entries_map_.erase(itr);
 
   // The entry we're about to delete is our caller, however its' still fine to
   // delete it.
   delete entry;
 }
 
 }  // namespace task_management