Add support for backgrounding processes on the Mac

content/browser/renderer_host/render_process_host_impl.cc

-// 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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
 #include <limits>
@@ skipping 2233 matching lines @@
 #endif  // OS_WIN
 
 #if defined(OS_WIN)
   // Same as below, but bound to an experiment (http://crbug.com/458594)
   // initially on Windows. Enabled by default in the asbence of field trials to
   // get coverage on the perf waterfall.
   base::FieldTrial* trial =
       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
   // tasks executing at lowered priority ahead of it or simply by not being
   // swiftly scheduled by the OS per the low process priority
   // (http://crbug.com/398103).
   child_process_launcher_->SetProcessBackgrounded(backgrounded);
 #endif  // OS_WIN
 
   // Notify the child process of background state.
@@ skipping 215 matching lines @@
   if (worker_ref_count_ == 0)
     Cleanup();
 }
 
 void RenderProcessHostImpl::GetAudioOutputControllers(
     const GetAudioOutputControllersCallback& callback) const {
   audio_renderer_host()->GetOutputControllers(callback);
 }
 
 }  // namespace content