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

chrome/renderer/render_thread.cc

 // Copyright (c) 2010 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.
 
 #include "chrome/renderer/render_thread.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 287 matching lines @@
 
 #if defined(OS_POSIX)
   suicide_on_channel_error_filter_ = new SuicideOnChannelErrorFilter;
   AddFilter(suicide_on_channel_error_filter_.get());
 #endif
 
   // Establish a channel to the GPU process asynchronously if requested. If the
   // 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() ||
       CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kPrelaunchGpuProcess)) {
     message_loop()->PostDelayedTask(FROM_HERE,
                                     task_factory_->NewRunnableMethod(
                                         &RenderThread::EstablishGpuChannel),
                                     kPrelauchGpuProcessDelayMS);
   }
@@ skipping 823 matching lines @@
   }
 
   return false;
 }
 
 void RenderThread::RegisterExtension(v8::Extension* extension,
                                      bool restrict_to_extensions) {
   WebScriptController::registerExtension(extension);
   v8_extensions_[extension->name()] = restrict_to_extensions;
 }