content: Increase thread priority for display critical IO threads on ChromeOS.

content/gpu/gpu_process.h

 // 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.
 
 #ifndef CONTENT_GPU_GPU_PROCESS_H_
 #define CONTENT_GPU_GPU_PROCESS_H_
 
 #include "base/macros.h"
 #include "content/child/child_process.h"
 
 namespace content {
 
 class GpuProcess : public ChildProcess {
  public:
-  GpuProcess();
+  explicit GpuProcess(base::ThreadPriority io_thread_priority);
   ~GpuProcess() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GpuProcess);
 };
 
 }
 
 #endif  // CONTENT_GPU_GPU_PROCESS_H_