Use a valid /prefetch argument when launching a process.

components/crash/content/app/crashpad_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/crash/content/app/crashpad.h"
 
 #include <stddef.h>
 
 #include "base/environment.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/path_service.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "components/crash/content/app/crash_reporter_client.h"
+#include "components/startup_metric_utils/common/pre_read_field_trial_utils_win.h"
 #include "third_party/crashpad/crashpad/client/crashpad_client.h"
 #include "third_party/crashpad/crashpad/client/crashpad_info.h"
 #include "third_party/crashpad/crashpad/client/simulate_crash_win.h"
 
 namespace crash_reporter {
 namespace internal {
 
 namespace {
 
 base::LazyInstance<crashpad::CrashpadClient>::Leaky g_crashpad_client =
@@ skipping 48 matching lines @@
 
     // In test binaries, use crashpad_handler directly. Otherwise, we launch
     // chrome.exe with --type=crashpad-handler.
     base::FilePath exe_file;
     CHECK(PathService::Get(base::FILE_EXE, &exe_file));
     if (exe_file.BaseName().value() != FILE_PATH_LITERAL("chrome.exe")) {
       base::FilePath exe_dir = exe_file.DirName();
       exe_file = exe_dir.Append(FILE_PATH_LITERAL("crashpad_handler.exe"));
     } else {
       arguments.push_back("--type=crashpad-handler");
+
+      if (startup_metric_utils::GetPreReadOptions().use_prefetch_argument) {
+        // The prefetch argument added here has to be documented in
+        // chrome_switches.cc, below the kPrefetchArgument* constants. A
+        // constant can't be used here because crashpad can't depend on Chrome.
+        arguments.push_back("/prefetch:7");
+      }
     }
 
     // TODO(scottmg): See https://crashpad.chromium.org/bug/23.
     arguments.push_back("--no-rate-limit");
 
     result = g_crashpad_client.Get().StartHandler(
         exe_file, database_path, url, process_annotations, arguments, false);
 
     // If we're the browser, push the pipe name into the environment so child
     // processes can connect to it. If we inherited another crashpad_handler's
@@ skipping 168 matching lines @@
 void __declspec(dllexport) __cdecl UnregisterNonABICompliantCodeRange(
     void* start) {
   ExceptionHandlerRecord* record =
       reinterpret_cast<ExceptionHandlerRecord*>(start);
 
   CHECK(RtlDeleteFunctionTable(&record->runtime_function));
 }
 #endif  // ARCH_CPU_X86_64
 
 }  // extern "C"