[BUG] ffmpeg dependency check breaks on Linux even if screencast is not used

[anthonychu]

Context:

• Playwright Version: 1.4.0
• Operating System: Linux (Azure Functions Linux Consumption plan)
• Node.js version: 12.x
• Browser: Chromium
• Extra: [any specific details about your environment]

The new ffmpeg dependency check is a breaking change on Linux because it now expects ffmpeg in the path. Is it possible to only run the check when video recording is activated?

Code Snippet

This app, with the playwright version bumped to 1.4.0. https://github.com/anthonychu/functions-headless-chromium/tree/main/playwright

Exception: Error: browserType.launch: Host system is missing dependencies!

  Install missing packages with:
      sudo apt-get install ffmpeg


Note: use DEBUG=pw:api environment variable and rerun to capture Playwright logs.
Stack: browserType.launch: Host system is missing dependencies!

  Install missing packages with:
      sudo apt-get install ffmpeg


Note: use DEBUG=pw:api environment variable and rerun to capture Playwright logs.
    at BrowserType._wrapApiCall (/home/site/wwwroot/node_modules/playwright-chromium/lib/client/channelOwner.js:76:15)
    at BrowserType.launch (/home/site/wwwroot/node_modules/playwright-chromium/lib/client/browserType.js:48:21)
    at module.exports (/home/site/wwwroot/screenshot/index.js:5:37)
    at WorkerChannel.invocationRequest (/azure-functions-host/workers/node/worker-bundle.js:18518:26)
    at ClientDuplexStream.<anonymous> (/azure-functions-host/workers/node/worker-bundle.js:18324:30)
    at ClientDuplexStream.emit (events.js:315:20)
    at addChunk (_stream_readable.js:295:12)
    at readableAddChunk (_stream_readable.js:271:9)
    at ClientDuplexStream.Readable.push (_stream_readable.js:212:10)
    at Object.onReceiveMessage (/azure-functions-host/workers/node/worker-bundle.js:22785:19)

@arjun27

[anthonychu]

Dupe of #3845 (got an error from GitHub after first try)