Make old task manager tests work against new task manager.

chrome/browser/ui/task_manager/task_manager_table_model.h

Index: chrome/browser/ui/task_manager/task_manager_table_model.h
diff --git a/chrome/browser/ui/task_manager/task_manager_table_model.h b/chrome/browser/ui/task_manager/task_manager_table_model.h
index bd175a9a6bc473a3829f4ee1b207ad57f075339e..ef4b352c4ccb2cea3232048b75c98f8b0b7864cf 100644
--- a/chrome/browser/ui/task_manager/task_manager_table_model.h
+++ b/chrome/browser/ui/task_manager/task_manager_table_model.h
@@ -14,6 +14,12 @@
 #include "chrome/browser/task_management/task_manager_observer.h"
 #include "ui/base/models/table_model.h"
 
+namespace task_manager {
+namespace browsertest_util {
+class TaskManagerTesterImpl;
+}
+}
+
 namespace task_management {
 
 class TaskManagerValuesStringifier;
@@ -101,6 +107,8 @@ class TaskManagerTableModel
   void ToggleColumnVisibility(int column_id);
 
  private:
+  friend class task_manager::browsertest_util::TaskManagerTesterImpl;
+
   // Start / stop observing the task manager.
   void StartUpdating();
   void StopUpdating();