Make old task manager tests work against new task manager.

chrome/browser/task_management/sampling/task_manager_impl.h

 // 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.
 
 #ifndef CHROME_BROWSER_TASK_MANAGEMENT_SAMPLING_TASK_MANAGER_IMPL_H_
 #define CHROME_BROWSER_TASK_MANAGEMENT_SAMPLING_TASK_MANAGER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 75 matching lines @@
 
   // content::GpuDataManagerObserver:
   void OnVideoMemoryUsageStatsUpdate(
       const gpu::VideoMemoryUsageStats& gpu_memory_stats) override;
 
   // The notification method on the UI thread when multiple bytes are read
   // from URLRequests. This will be called by the |io_thread_helper_|
   static void OnMultipleBytesReadUI(std::vector<BytesReadParam>* params);
 
  private:
+  friend class TaskManagerTester;
   friend struct base::DefaultLazyInstanceTraits<TaskManagerImpl>;
 
   TaskManagerImpl();
 
   // task_management::TaskManagerInterface:
   void Refresh() override;
   void StartUpdating() override;
   void StopUpdating() override;
 
   // Based on |param| the appropriate task will be updated by its network usage.
@@ skipping 44 matching lines @@
   // This will be set to true while there are observers and the task manager is
   // running.
   bool is_running_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskManagerImpl);
 };
 
 }  // namespace task_management
 
 #endif  // CHROME_BROWSER_TASK_MANAGEMENT_SAMPLING_TASK_MANAGER_IMPL_H_