Remove code related to the PreReadChromeChildInBrowser field trial.

chrome/app/main_dll_loader_win.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/app/main_dll_loader_win.h"
 
 #include <windows.h>  // NOLINT
 #include <shlwapi.h>  // NOLINT
 #include <stddef.h>
 #include <userenv.h>  // NOLINT
@@ skipping 44 matching lines @@
 
 // Loads |module| after setting the CWD to |module|'s directory. Returns a
 // reference to the loaded module on success, or null on error.
 HMODULE LoadModuleWithDirectory(const base::FilePath& module) {
   ::SetCurrentDirectoryW(module.DirName().value().c_str());
 
   const startup_metric_utils::PreReadOptions pre_read_options =
       startup_metric_utils::GetPreReadOptions();
 
   // If enabled by the PreRead field trial, pre-read the binary to avoid a lot
-  // of random IO. Don't pre-read the binary if it is chrome_child.dll and the
-  // |pre_read_chrome_child_in_browser| option is enabled; the binary should
-  // already have been pre-read by the browser process in that case.
-  if (pre_read_options.pre_read &&
-      (!pre_read_options.pre_read_chrome_child_in_browser ||
-       module.BaseName().value() != installer::kChromeChildDll)) {
+  // of random IO.
+  if (pre_read_options.pre_read)
     PreReadFile(module, pre_read_options);
-  }
 
   return ::LoadLibraryExW(module.value().c_str(), nullptr,
                           LOAD_WITH_ALTERED_SEARCH_PATH);
 }
 
 void RecordDidRun(const base::FilePath& dll_path) {
   bool system_level = !InstallUtil::IsPerUserInstall(dll_path);
   GoogleUpdateSettings::UpdateDidRunState(true, system_level);
 }
 
@@ skipping 169 matching lines @@
   }
 };
 
 MainDllLoader* MakeMainDllLoader() {
 #if defined(GOOGLE_CHROME_BUILD)
   return new ChromeDllLoader();
 #else
   return new ChromiumDllLoader();
 #endif
 }