Add support for backgrounding processes on the Mac

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 1e20d8e6a899b551bc85a4362a7507ebdfb8bf39..9db94a14a517355c97b626d50900172c96826425 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright 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.
 
@@ -2252,6 +2252,12 @@ void RenderProcessHostImpl::SetBackgrounded(bool backgrounded) {
       base::FieldTrialList::Find("BackgroundRendererProcesses");
   if (!trial || trial->group_name() != "Disallow")
     child_process_launcher_->SetProcessBackgrounded(backgrounded);
+#elif defined(OS_MACOSX)
+  const std::string trial_group_name =
+      base::FieldTrialList::FindFullName("BackgroundRendererProcesses");
+  if (trial_group_name.length() > 0 && trial_group_name != "Disallow") {
+    child_process_launcher_->SetProcessBackgrounded(backgrounded);
+  }
 #else
   // Control the background state from the browser process, otherwise the task
   // telling the renderer to "unbackground" itself may be preempted by other