Use a valid /prefetch argument when launching a process.

components/startup_metric_utils/common/pre_read_field_trial_utils_win.h

Index: components/startup_metric_utils/common/pre_read_field_trial_utils_win.h
diff --git a/components/startup_metric_utils/common/pre_read_field_trial_utils_win.h b/components/startup_metric_utils/common/pre_read_field_trial_utils_win.h
index cacf4b389cc7762c1299e1cee82b68d5f8d2a229..bfa708b0952f6f326ae6bbf9599396ef7601dd69 100644
--- a/components/startup_metric_utils/common/pre_read_field_trial_utils_win.h
+++ b/components/startup_metric_utils/common/pre_read_field_trial_utils_win.h
@@ -21,8 +21,8 @@ using RegisterPreReadSyntheticFieldTrialCallback =
 
 // The options controlled by the PreRead field trial.
 struct PreReadOptions {
-  // No explicit DLL pre-reading.
-  bool no_pre_read;
+  // Pre-read DLLs explicitly.
+  bool pre_read;
 
   // Pre-read DLLs with a high thread priority.
   bool high_priority;
@@ -32,6 +32,9 @@ struct PreReadOptions {
 
   // Pre-read DLLs using the ::PrefetchVirtualMemory function, if available.
   bool prefetch_virtual_memory;
+
+  // Use a /prefetch argument when launching a process.
+  bool prefetch_argument;
 };
 
 // Initializes DLL pre-reading options from the registry.