Use a valid /prefetch argument when launching a process.

content/public/common/prefetch_argument_win.cc

Index: content/public/common/prefetch_argument_win.cc
diff --git a/content/public/common/prefetch_argument_win.cc b/content/public/common/prefetch_argument_win.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9a75bf43933924ccdb0fd0f04882b14b4cfbcc70
--- /dev/null
+++ b/content/public/common/prefetch_argument_win.cc
@@ -0,0 +1,31 @@
+// Copyright (c) 2016 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 "content/public/common/prefetch_argument_win.h"
+
+#include "base/command_line.h"
+#include "base/logging.h"
+#include "base/strings/stringprintf.h"
+#include "components/startup_metric_utils/common/pre_read_field_trial_utils_win.h"
+
+namespace content {
+
+void AddWindowsPrefetchArgument(int prefetch_id,
+                                base::CommandLine* command_line) {
+  DCHECK(command_line);
+
+  // There can only be 9 different prefetch profiles per executable.
+  DCHECK_GE(prefetch_id, 0);
+  DCHECK_LE(prefetch_id, 8);
+
+  if (startup_metric_utils::GetPreReadOptions() &
+      startup_metric_utils::PRE_READ_OPTION_NO_PREFETCH_ARGUMENT) {
+    return;
+  }
+
+  if (prefetch_id != 0)
+    command_line->AppendArg(base::StringPrintf("/prefetch:%d", prefetch_id));
+}
+
+}  // namespace content