--disable-features=WebVrVsyncAlign is no longer being properly applied during VR Telemetry tests, which is causing performance regressions to be reported.

The cause is https://chromium.googlesource.com/catapult.git/+/ed32dd50b3276262cb0ce22691b8f263955b0577, although all that did was expose an existing bug in Telemetry.

Chrome only works with one instance each of --disable-features, --enable-features, and --force-field-trials - if multiple instances are in the command line, then Chrome uses whatever it parses last.

Telemetry blindly appends extra browser arguments from a Page to the list, so if one of the above switches is used in a Page's extra args, then there will be multiple usage instances.

Before being passed to Chrome, Telemetry puts all the command line flags into a set to remove duplicates. Prior to the above CL, an additional feature was appended to the end of all --disable-features switches, which caused the --disable-features instance with WebVrVsyncAlign to appear last in the set. With the above CL, WebVrVsyncAlign now appears before another --disable-features instance, so it gets overridden.

The solution for this is to have Telemetry manually merge multiple instances of the offending switches before passing them to Chrome.