It is a method in desktop:
https://cs.chromium.org/chromium/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome/desktop_browser_finder.py?rcl=8a42ad3cb185e340c32b20f657980fd057e3769f&l=182

And a property on the base class:
https://cs.chromium.org/chromium/src/third_party/catapult/telemetry/telemetry/internal/browser/possible_browser.py?rcl=8a42ad3cb185e340c32b20f657980fd057e3769f&l=139

It causes errors such as:

$ tools/perf/run_benchmark system_health.common_mobile --story-filter load:news:cnn
WARNING:root:Unable to import cv2 due to: libjpeg.so.8: cannot open shared object file: No such file or directory
(WARNING) 2018-02-23 10:00:31,837 desktop_browser_finder.FindAllAvailableBrowsers:242  Chrome build location for linux_x86_64 not found. Browser will be run without Flash.

Traceback (most recent call last):
  <module> at /usr/local/google/code/clankium/src/tools/perf/run_benchmark:27
    sys.exit(main())
  main at /usr/local/google/code/clankium/src/tools/perf/run_benchmark:23
    return benchmark_runner.main(config, [trybot_command.Trybot])
  main at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/benchmark_runner.py:376
    return command_instance.Run(options)
  Run at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/benchmark_runner.py:246
    return min(255, b.Run(args))
  Run at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/benchmark.py:100
    return story_runner.RunBenchmark(self, finder_options)
  RunBenchmark at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/internal/story_runner.py:292
    benchmark.CustomizeBrowserOptions(finder_options.browser_options)
  CustomizeBrowserOptions at /usr/local/google/code/clankium/src/tools/perf/core/perf_benchmark.py:40
    variations = self._GetVariationsBrowserArgs(options.finder_options)
  _GetVariationsBrowserArgs at /usr/local/google/code/clankium/src/tools/perf/core/perf_benchmark.py:57
    possible_browser = browser_finder.FindBrowser(finder_options)
  Cacher at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/decorators.py:35
    cacher.__cache[key] = obj(*args, **kwargs)
  FindBrowser at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/internal/browser/browser_finder.py:78
    key=lambda b: b.last_modification_time())[-1]
  <lambda> at /usr/local/google/code/clankium/src/third_party/catapult/telemetry/telemetry/internal/browser/browser_finder.py:78
    key=lambda b: b.last_modification_time())[-1]
TypeError: 'int' object is not callable

Locals:
  b : PossibleAndroidBrowser(browser_type=android-webview)