Change the new-task-manager flag so that the new implementation is enabled by default for all users.

chrome/browser/task_manager/task_manager_browsertest.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 "chrome/browser/task_manager/task_manager.h"
 
 #include "base/files/file_path.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 100 matching lines @@
       if (title == model()->GetResourceTitle(i))
         return i;
     }
     return -1;
   }
 
  protected:
   void SetUpCommandLine(base::CommandLine* command_line) override {
     ExtensionBrowserTest::SetUpCommandLine(command_line);
 
+    // These tests are for the old implementation of the task manager. We must
+    // explicitly disable the new one.
+    task_manager::browsertest_util::EnableOldTaskManager();
+
     // Do not launch device discovery process.
     command_line->AppendSwitch(switches::kDisableDeviceDiscoveryNotifications);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TaskManagerBrowserTest);
 };
 
 class TaskManagerUtilityProcessBrowserTest : public TaskManagerBrowserTest {
  public:
@@ skipping 1072 matching lines @@
       WaitForTaskManagerRows(1, MatchTab("Title Of Awesomeness")));
   ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(0, MatchAnySubframe()));
 
   HideTaskManager();
   ShowTaskManager();
 
   ASSERT_NO_FATAL_FAILURE(
       WaitForTaskManagerRows(1, MatchTab("Title Of Awesomeness")));
   ASSERT_NO_FATAL_FAILURE(WaitForTaskManagerRows(0, MatchAnySubframe()));
 }