Critical Bug: Multiple --enable-features and --disable-features arguments are overwritten

In Chromium and Cobalt, base::CommandLine parses command-line arguments into a map where each switch key can only have a single value. If a switch like --enable-features or --disable-features is specified multiple times on the command line, only the last occurrence's value is preserved, and all previous ones are overwritten and ignored.

By changing the code to append separate --enable-features=... arguments for each feature instead of joining them with a comma into a single --enable-features argument, only the last enabled feature in the list will actually be enabled. All other features will be silently ignored.

Suggested Fix

Revert this change and continue to collect all enabled/disabled features using a StringJoiner (or List<String>) and append a single --enable-features=... and --disable-features=... argument to extraCommandLineArgs at the end of the method, for example:

public static List<String> getExtraCommandLineArgs(Map<String, String> javaSwitches) {
    List<String> extraCommandLineArgs = new ArrayList<>();
    StringJoiner jsFlags = new StringJoiner(";");
    StringJoiner enabledFeatures = new StringJoiner(",");
    StringJoiner disabledFeatures = new StringJoiner(",");

    if (javaSwitches.containsKey(JavaSwitches.USE_IPV4_FOR_DNS)) {
        enabledFeatures.add("UseIPv4ForDNS");
    }
    // ... collect other features ...

    if (enabledFeatures.length() > 0) {
        extraCommandLineArgs.add("--enable-features=" + enabledFeatures.toString());
    }
    if (disabledFeatures.length() > 0) {
        extraCommandLineArgs.add("--disable-features=" + disabledFeatures.toString());
    }
    return extraCommandLineArgs;
}