Remove code related to the PreReadChromeChildInBrowser field trial.

components/startup_metric_utils/common/pre_read_field_trial_utils_win.cc

 // Copyright 2015 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 "components/startup_metric_utils/common/pre_read_field_trial_utils_win.h"
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
@@ skipping 15 matching lines @@
 const char kPreReadSyntheticFieldTrialName[] = "SyntheticPreRead";
 
 // Variation names for the PreRead field trial. All variations change the
 // default behavior, i.e. the default is the inverse of the variation. Thus,
 // variations that cancel something that is done by default have a negative
 // name.
 const base::char16 kNoPreReadVariationName[] = L"NoPreRead";
 const base::char16 kHighPriorityVariationName[] = L"HighPriority";
 const base::char16 kPrefetchVirtualMemoryVariationName[] =
     L"PrefetchVirtualMemory";
-const base::char16 kPreReadChromeChildInBrowser[] =
-    L"PreReadChromeChildInBrowser";
 
 // Registry key in which the PreRead field trial group is stored.
 const base::char16 kPreReadFieldTrialRegistryKey[] = L"\\PreReadFieldTrial";
 
 // Pre-read options to use for the current process. This is initialized by
 // InitializePreReadOptions().
 PreReadOptions g_pre_read_options = {};
 
 // Returns the registry path in which the PreRead group is stored.
 base::string16 GetPreReadRegistryPath(
@@ skipping 22 matching lines @@
   const base::string16 registry_path =
       GetPreReadRegistryPath(product_registry_path);
   const base::win::RegKey key(HKEY_CURRENT_USER, registry_path.c_str(),
                               KEY_QUERY_VALUE);
 
   // Set the PreRead field trial's options.
   g_pre_read_options.pre_read = !ReadBool(key, kNoPreReadVariationName);
   g_pre_read_options.high_priority = ReadBool(key, kHighPriorityVariationName);
   g_pre_read_options.prefetch_virtual_memory =
       ReadBool(key, kPrefetchVirtualMemoryVariationName);
-  g_pre_read_options.pre_read_chrome_child_in_browser =
-      ReadBool(key, kPreReadChromeChildInBrowser);
 }
 
 PreReadOptions GetPreReadOptions() {
   return g_pre_read_options;
 }
 
 void UpdatePreReadOptions(const base::string16& product_registry_path) {
   DCHECK(!product_registry_path.empty());
 
   const base::string16 registry_path =
@@ skipping 50 matching lines @@
   base::string16 group;
   key.ReadValue(L"", &group);
 
   if (!group.empty()) {
     register_synthetic_field_trial.Run(kPreReadSyntheticFieldTrialName,
                                        base::UTF16ToUTF8(group));
   }
 }
 
 }  // namespace startup_metric_utils