Remove support for AllowBelowNormalFromBrowser experiment group.

base/process/process_win.cc

Index: base/process/process_win.cc
diff --git a/base/process/process_win.cc b/base/process/process_win.cc
index 30cd9dc737268e01c557c3def27bada318c20b93..818864fa528dbab283e975983683ed337c3753e1 100644
--- a/base/process/process_win.cc
+++ b/base/process/process_win.cc
@@ -6,10 +6,8 @@
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/metrics/field_trial.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/process/kill.h"
-#include "base/strings/string_util.h"
 #include "base/win/windows_version.h"
 
 namespace {
@@ -179,23 +177,7 @@ bool Process::SetProcessBackgrounded(bool value) {
     priority = value ? PROCESS_MODE_BACKGROUND_BEGIN :
                        PROCESS_MODE_BACKGROUND_END;
   } else {
-    // Experiment (http://crbug.com/458594) with using IDLE_PRIORITY_CLASS as a
-    // background priority for background renderers (this code path is
-    // technically for more than just the renderers but they're the only use
-    // case in practice and experimenting here direclty is thus easier -- plus
-    // it doesn't really hurt as above we already state our intent of using
-    // PROCESS_MODE_BACKGROUND_BEGIN if available which is essentially
-    // IDLE_PRIORITY_CLASS plus lowered IO priority). Enabled by default in the
-    // asbence of field trials to get coverage on the perf waterfall.
-    DWORD background_priority = IDLE_PRIORITY_CLASS;
-    base::FieldTrial* trial =
-        base::FieldTrialList::Find("BackgroundRendererProcesses");
-    if (trial && StartsWith(trial->group_name(), "AllowBelowNormalFromBrowser",
-                            CompareCase::SENSITIVE)) {
-      background_priority = BELOW_NORMAL_PRIORITY_CLASS;
-    }
-
-    priority = value ? background_priority : NORMAL_PRIORITY_CLASS;
+    priority = value ? IDLE_PRIORITY_CLASS : NORMAL_PRIORITY_CLASS;
   }
 
   return (::SetPriorityClass(Handle(), priority) != 0);