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

Index: chrome/browser/task_manager/task_manager_browsertest.cc
diff --git a/chrome/browser/task_manager/task_manager_browsertest.cc b/chrome/browser/task_manager/task_manager_browsertest.cc
index 888da368a205ba95fd8e8e6a91c908d2f9f75f8e..f58312446ffabf5912ad35d702675bb2e5b3e528 100644
--- a/chrome/browser/task_manager/task_manager_browsertest.cc
+++ b/chrome/browser/task_manager/task_manager_browsertest.cc
@@ -118,6 +118,10 @@ class TaskManagerBrowserTest : public ExtensionBrowserTest {
   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);
   }