Task Manager Should remember the most recently enabled columns.

chrome/browser/task_management/providers/child_process_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/child_process_task_provider.h"
 
 #include "base/process/process.h"
 #include "base/stl_util.h"
 #include "chrome/browser/task_management/providers/child_process_task.h"
 #include "content/public/browser/browser_child_process_host_iterator.h"
@@ skipping 105 matching lines @@
 
   for (auto& process_data : *child_processes)
     CreateTask(process_data);
 
   // Now start observing.
   BrowserChildProcessObserver::Add(this);
 }
 
 void ChildProcessTaskProvider::CreateTask(
     const content::ChildProcessData& data) {
-  // The following case should never happen since we start observing
-  // |BrowserChildProcessObserver| only after we collect all pre-existing child
-  // processes and are notified (on the UI thread) that the collection is
-  // completed at |ChildProcessDataCollected()|.
   if (tasks_by_handle_.find(data.handle) != tasks_by_handle_.end()) {
-    NOTREACHED();
+    // This case can happen when some of the child process data we collect upon
+    // StartUpdating() might be of BrowserChildProcessHosts whose channels
+    // hadn't connected yet. So we just return.
     return;
   }
 
   // Create the task and notify the observer.
   ChildProcessTask* task = new ChildProcessTask(data);
   tasks_by_handle_[data.handle] = task;
   tasks_by_pid_[task->process_id()] = task;
   NotifyObserverTaskAdded(task);
 }
 
@@ skipping 13 matching lines @@
 
   NotifyObserverTaskRemoved(task);
 
   // Finally delete the task.
   tasks_by_handle_.erase(itr);
   tasks_by_pid_.erase(task->process_id());
   delete task;
 }
 
 }  // namespace task_management