base: Allow renderer thread priorities to be changed.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 80f8fcd17814f699b7382783da0b446512dd541c..5b02de25eb6229dece6c31cec0427fa2dea56565 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -854,6 +854,13 @@ void RenderThreadImpl::Init(
   GetRemoteInterfaces()->GetInterface(
       mojo::GetProxy(&storage_partition_service_));
 
+#if defined(OS_LINUX)
+  ChildProcess::current()->SetIOThreadPriority(base::ThreadPriority::DISPLAY);
+  ChildThreadImpl::current()->SetThreadPriority(
+      categorized_worker_pool_->background_worker_thread_id(),
+      base::ThreadPriority::BACKGROUND);
+#endif
+
   is_renderer_suspended_ = false;
 }
 
@@ -1130,6 +1137,10 @@ void RenderThreadImpl::InitializeCompositorThread() {
   compositor_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(base::IgnoreResult(&ThreadRestrictions::SetIOAllowed), false));
+#if defined(OS_LINUX)
+  ChildThreadImpl::current()->SetThreadPriority(compositor_thread_->threadId(),
+                                                base::ThreadPriority::DISPLAY);
+#endif
 
   SynchronousInputHandlerProxyClient* synchronous_input_handler_proxy_client =
       nullptr;