Remove the current /prefetch switch when relaunching Chrome.

chrome/common/switch_utils.cc

 // Copyright (c) 2011 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/common/switch_utils.h"
 
 #include <stddef.h>
 
 #include "base/macros.h"
+#include "build/build_config.h"
 #include "chrome/common/chrome_switches.h"
 
+#if defined(OS_WIN)
+#include "base/strings/string_util.h"
+#endif  // defined(OS_WIN)
+
 namespace switches {
 
+namespace {
+
 // Switches enumerated here will be removed when a background instance of
 // Chrome restarts itself. If your key is designed to only be used once,
 // or if it does not make sense when restarting a background instance to
 // pick up an automatic update, be sure to add it to this list.
 const char* const kSwitchesToRemoveOnAutorestart[] = {
   switches::kApp,
   switches::kAppId,
   switches::kForceFirstRun,
   switches::kMakeDefaultBrowser,
   switches::kNoStartupWindow,
   switches::kRestoreLastSession,
   switches::kShowAppList,
   switches::kWinJumplistAction
 };
 
+}  // namespace
+
 void RemoveSwitchesForAutostart(
     std::map<std::string, base::CommandLine::StringType>* switch_list) {
   for (size_t i = 0; i < arraysize(kSwitchesToRemoveOnAutorestart); ++i)
     switch_list->erase(kSwitchesToRemoveOnAutorestart[i]);
+
+#if defined(OS_WIN)
+  // The relaunched browser process shouldn't reuse the /prefetch:# switch of
+  // the current process because the process type can change (e.g. a process
+  // initially launched in background can be relaunched in foreground).
+  static const char kPrefetchSwitchPrefix[] = "prefetch:";
+  auto it = switch_list->lower_bound(kPrefetchSwitchPrefix);
+  if (it != switch_list->end() &&
+      base::StartsWith(it->first, kPrefetchSwitchPrefix,
+                       base::CompareCase::SENSITIVE)) {
+    switch_list->erase(it);
+  }
+#endif  // defined(OS_WIN)
 }
 
 }  // namespace switches