Feature to disable field trials in old versions of Chromium. Field trials...

chrome/renderer/render_thread.cc

Index: chrome/renderer/render_thread.cc
===================================================================
--- chrome/renderer/render_thread.cc	(revision 71223)
+++ chrome/renderer/render_thread.cc	(working copy)
@@ -305,8 +305,10 @@
   // channel is established in time, EstablishGpuChannelSync will not block when
   // it is later called. Delays by a fixed period of time to avoid loading the
   // GPU immediately in an attempt to not slow startup time.
+  // After June 30, 2011 builds, it will always be in defaut group.
   scoped_refptr<base::FieldTrial> prelaunch_trial(
-      new base::FieldTrial("PrelaunchGpuProcessExperiment", 100));
+      new base::FieldTrial("PrelaunchGpuProcessExperiment", 100,
+          "default_prelaunch_gpu_process", 2011, 6, 30));

[jar (doing other things), 2011/01/15 20:52:47]

nit: better may be to add "_default" as a postfix instead of a prexfix, so that
if there is a new histogram, it will alphabetize next to the non-default case.

Better yet may be to speak with GPU folks and see why we don't have a second
group name.  I suspect this was a bug.

   int prelaunch_group = prelaunch_trial->AppendGroup("prelaunch_gpu_process",
                                                      kPrelauchGpuPercentage);
   if (prelaunch_group == prelaunch_trial->group() ||