Do not set background priority in-process on Windows

content/browser/child_process_launcher.cc

Index: content/browser/child_process_launcher.cc
diff --git a/content/browser/child_process_launcher.cc b/content/browser/child_process_launcher.cc
index a0dc5b72837af368cbd3aaca21320576f528218a..5e65042301c9a9fff4e1fcad92a37379c4d22658 100644
--- a/content/browser/child_process_launcher.cc
+++ b/content/browser/child_process_launcher.cc
@@ -510,13 +510,11 @@ base::TerminationStatus ChildProcessLauncher::GetChildTerminationStatus(
 }
 
 void ChildProcessLauncher::SetProcessBackgrounded(bool background) {
-  // TODO(wfh): re-enable this after testing if dropping the priority of
-  // backgrounded tabs is the root cause of http://crbug.com/381820.
-  // BrowserThread::PostTask(
-  //     BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
-  //     base::Bind(
-  //         &ChildProcessLauncher::Context::SetProcessBackgrounded,
-  //         GetHandle(), background));
+  BrowserThread::PostTask(
+     BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
+     base::Bind(
+         &ChildProcessLauncher::Context::SetProcessBackgrounded,
+         GetHandle(), background));
 }
 
 void ChildProcessLauncher::SetTerminateChildOnShutdown(