Allow overriding variation parameter via chrome://flags.

chrome/browser/chrome_browser_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 "chrome/browser/chrome_browser_main.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
@@ skipping 700 matching lines @@
     // X-Client-Data request header.
     variations::VariationsHttpHeaderProvider* provider =
         variations::VariationsHttpHeaderProvider::GetInstance();
     bool result = provider->SetDefaultVariationIds(
         command_line->GetSwitchValueASCII(switches::kForceVariationIds));
     CHECK(result) << "Invalid --" << switches::kForceVariationIds
                   << " list specified.";
     metrics->AddSyntheticTrialObserver(provider);
   }
 
+  // Associate parameters chosen in about:flags and create trial/group for them.
+  flags_ui::PrefServiceFlagsStorage flags_storage(
+      g_browser_process->local_state());
+  about_flags::RegisterAllFeatureVariationParameters(&flags_storage);
+
   std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
   feature_list->InitializeFromCommandLine(
       command_line->GetSwitchValueASCII(switches::kEnableFeatures),
       command_line->GetSwitchValueASCII(switches::kDisableFeatures));
 
 #if defined(FIELDTRIAL_TESTING_ENABLED)
   if (!command_line->HasSwitch(switches::kDisableFieldTrialTestingConfig) &&
       !command_line->HasSwitch(switches::kForceFieldTrials) &&
       !command_line->HasSwitch(variations::switches::kVariationsServerURL)) {
     chrome_variations::AssociateDefaultFieldTrialConfig(feature_list.get());
@@ skipping 232 matching lines @@
 
 #if !defined(OS_CHROMEOS)
   // Convert active labs into switches. This needs to be done before
   // ResourceBundle::InitSharedInstanceWithLocale as some loaded resources are
   // affected by experiment flags (--touch-optimized-ui in particular).
   // On ChromeOS system level flags are applied from the device settings from
   // the session manager.
   {
     TRACE_EVENT0("startup",
         "ChromeBrowserMainParts::PreCreateThreadsImpl:ConvertFlags");
-    flags_ui::PrefServiceFlagsStorage flags_storage_(
+    flags_ui::PrefServiceFlagsStorage flags_storage(
         g_browser_process->local_state());
-    about_flags::ConvertFlagsToSwitches(&flags_storage_,
+    about_flags::ConvertFlagsToSwitches(&flags_storage,
                                         base::CommandLine::ForCurrentProcess(),
                                         flags_ui::kAddSentinels);
   }
 #endif  // !defined(OS_CHROMEOS)
   // The MaterialDesignController needs to look at command line flags, which
   // are not available until this point. Now that they are, proceed with
   // initializing the MaterialDesignController.
   ui::MaterialDesignController::Initialize();
 #if defined(OS_CHROMEOS)
   ash::MaterialDesignController::Initialize();
@@ skipping 1007 matching lines @@
   chromeos::CrosSettings::Shutdown();
 #endif  // defined(OS_CHROMEOS)
 #endif  // defined(OS_ANDROID)
 }
 
 // Public members:
 
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }