content: Improve thread priority for raster threads.

content/renderer/render_thread_impl.cc

 // 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.
 
 #include "content/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <utility>
@@ skipping 810 matching lines @@
   DCHECK_GT(num_raster_threads, 0);
 
 #if defined(OS_ANDROID)
   // Note: Currently, enabling image decode tasks only provides a benefit if
   // we use high quality interpolation filters, which are disabled on android.
   are_image_decode_tasks_enabled_ = false;
 #else
   are_image_decode_tasks_enabled_ = true;
 #endif
 
-  base::SimpleThread::Options thread_options;
-#if defined(OS_ANDROID) || defined(OS_LINUX)
-  if (!command_line.HasSwitch(
-          switches::kUseNormalPriorityForTileTaskWorkerThreads)) {
-    thread_options.set_priority(base::ThreadPriority::BACKGROUND);
-  }
-#endif
-
-  raster_worker_pool_->Start(num_raster_threads, thread_options);
+  raster_worker_pool_->Start(num_raster_threads);
 
   // TODO(boliu): In single process, browser main loop should set up the
   // discardable memory manager, and should skip this if kSingleProcess.
   // See crbug.com/503724.
   base::DiscardableMemoryAllocator::SetInstance(
       ChildThreadImpl::discardable_shared_memory_manager());
 
   service_registry()->AddService<RenderFrameSetup>(
       base::Bind(CreateRenderFrameSetup));
   service_registry()->AddService<EmbeddedWorkerSetup>(
@@ skipping 1321 matching lines @@
 }
 
 void RenderThreadImpl::PendingRenderFrameConnect::OnConnectionError() {
   size_t erased =
       RenderThreadImpl::current()->pending_render_frame_connects_.erase(
           routing_id_);
   DCHECK_EQ(1u, erased);
 }
 
 }  // namespace content