browser: Make cmd line non-const in process singleton callback

The command line received in the process singleton callback needs to be
in order to prevent temporary communication data affecting the command
line processing code that runs on the receiving browser process.
So change the command line from const ref to a non-const passed by value
argument.

Bug: 40747285
Change-Id: I7534b44efa7b1f3302f08eb461c8957ba084d8ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5311256
Commit-Queue: Orko Garai <[email protected]>
Reviewed-by: Nick Yamane <[email protected]>
Reviewed-by: Greg Thompson <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1264348}
diff --git a/chrome/browser/chrome_process_singleton.h b/chrome/browser/chrome_process_singleton.h
index 3f3d55f..7567e5b9 100644
--- a/chrome/browser/chrome_process_singleton.h
+++ b/chrome/browser/chrome_process_singleton.h
@@ -61,7 +61,7 @@
   static bool IsSingletonInstance();
 
  private:
-  bool NotificationCallback(const base::CommandLine& command_line,
+  bool NotificationCallback(base::CommandLine command_line,
                             const base::FilePath& current_directory);
 
   // Whether or not this instance is the running single instance.