Enable FeatureList for the GPU process.

content/renderer/renderer_main.cc

 // Copyright (c) 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.
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/debug/leak_annotations.h"
 #include "base/feature_list.h"
 #include "base/i18n/rtl.h"
 #include "base/message_loop/message_loop.h"
-#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/pending_task.h"
 #include "base/strings/string_util.h"
 #include "base/sys_info.h"
 #include "base/threading/platform_thread.h"
 #include "base/timer/hi_res_timer_manager.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "components/scheduler/renderer/renderer_scheduler.h"
@@ skipping 122 matching lines @@
   bool no_sandbox = parsed_command_line.HasSwitch(switches::kNoSandbox);
 
   // Initialize histogram statistics gathering system.
   base::StatisticsRecorder::Initialize();
 
 #if defined(OS_ANDROID)
   // If we have a pending chromium android linker histogram, record it.
   base::android::RecordChromiumAndroidLinkerRendererHistogram();
 #endif
 
-  // Initialize statistical testing infrastructure.  We set the entropy provider
-  // to NULL to disallow the renderer process from creating its own one-time
-  // randomized trials; they should be created in the browser process.
-  base::FieldTrialList field_trial_list(NULL);
-  // Ensure any field trials in browser are reflected into renderer.
-  if (parsed_command_line.HasSwitch(switches::kForceFieldTrials)) {
-    bool result = base::FieldTrialList::CreateTrialsFromString(
-        parsed_command_line.GetSwitchValueASCII(switches::kForceFieldTrials),
-        std::set<std::string>());
-    DCHECK(result);
-  }
-
   std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
   feature_list->InitializeFromCommandLine(
       parsed_command_line.GetSwitchValueASCII(switches::kEnableFeatures),
       parsed_command_line.GetSwitchValueASCII(switches::kDisableFeatures));
   base::FeatureList::SetInstance(std::move(feature_list));

[Alexei Svitkine (slow), 2016/04/29 18:42:13]

How about removing this too and adding kRendererProcess to the switch?

[Alexei Svitkine (slow), 2016/04/29 18:43:05]

And by "switch", I of course mean "if" because apparently I confuse all the
constructs!

 
   std::unique_ptr<scheduler::RendererScheduler> renderer_scheduler(
       scheduler::RendererScheduler::Create());
 
   // PlatformInitialize uses FieldTrials, so this must happen later.
   platform.PlatformInitialize();
 
 #if defined(ENABLE_PLUGINS)
   // Load pepper plugins before engaging the sandbox.
   PepperPluginRegistry::GetInstance();
@@ skipping 42 matching lines @@
     // ignore shutdown-only leaks.
     __lsan_do_leak_check();
 #endif
   }
   platform.PlatformUninitialize();
   TRACE_EVENT_ASYNC_END0("startup", "RendererMain", 0);
   return 0;
 }
 
 }  // namespace content