It seems like whenever I run the webview startup benchmark in a particular checkout, it re-installs Monochrome (or systemwebviewgoogle) from that checkout. I would like to use this script to run benchmarks on a monochrome I install myself.

Can we add a --no-install flag to the script? This flag should prevent the script from reinstalling monochrome, and it should also *not* change the monochrome provider (it can assume I've already installed a suitable webview and set the monochrome provider).

To clarify, I run the webview startup benchmark with:

$ tools/perf/run_benchmark system_health.webview_startup --browser android-webview-google -v --pageset-repeat=1
$ # this command installs Monochrome, which I found very surprising (and not always what I want)

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Some use cases I have in mind:

 1. I want to install systemwebviewgoogle instead of monochrome. I always develop with systemwebviewgoogle on N+ because it builds and installs faster than monochrome. If the script requires monochrome, I have to spend extra time building and installing monochrome
 2. I want to install an official build from android-bourbon. I understand these builds will *not* use the GN arg "enable_profiling = true", but I assume that I can still get some useful information from such builds.
    * If I've misunderstood, and this configuration will *not* give any useful information, please let me know.