Turn ThreadPriority enum into an enum class.

gpu/command_buffer/service/async_pixel_transfer_manager_share_group.cc

 // Copyright 2013 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 "gpu/command_buffer/service/async_pixel_transfer_manager_share_group.h"
 
 #include <list>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
@@ skipping 29 matching lines @@
 
 // TODO(backer): Factor out common thread scheduling logic from the EGL and
 // ShareGroup implementations. http://crbug.com/239889
 class TransferThread : public base::Thread {
  public:
   TransferThread()
       : base::Thread(kAsyncTransferThreadName),
         initialized_(false) {
     Start();
 #if defined(OS_ANDROID) || defined(OS_LINUX)
-    SetPriority(base::kThreadPriority_Background);
+    SetPriority(base::ThreadPriority::BACKGROUND);
 #endif
   }
 
   ~TransferThread() override {
     // The only instance of this class was declared leaky.
     NOTREACHED();
   }
 
   void InitializeOnMainThread(gfx::GLContext* parent_context) {
     TRACE_EVENT0("gpu", "TransferThread::InitializeOnMainThread");
@@ skipping 481 matching lines @@
 
 AsyncPixelTransferDelegate*
 AsyncPixelTransferManagerShareGroup::CreatePixelTransferDelegateImpl(
     gles2::TextureRef* ref,
     const AsyncTexImage2DParams& define_params) {
   return new AsyncPixelTransferDelegateShareGroup(
       &shared_state_, ref->service_id(), define_params);
 }
 
 }  // namespace gpu