Remove support for AllowBackgroundModeFromRenderer group in BackgroundRendererProcesses experiment.

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 67670c0f886c7ff4aabfedca70e06e146b54a8e7..1e20d8e6a899b551bc85a4362a7507ebdfb8bf39 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -2250,10 +2250,8 @@ void RenderProcessHostImpl::SetBackgrounded(bool backgrounded) {
   // get coverage on the perf waterfall.
   base::FieldTrial* trial =
       base::FieldTrialList::Find("BackgroundRendererProcesses");
-  if (!trial || (trial->group_name() != "Disallow" &&
-                 trial->group_name() != "AllowBackgroundModeFromRenderer")) {
+  if (!trial || 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