Currently the (Android) scenario_app has very rudimentary logging, including dumping the full adb logcat to stdout:

1. Starting adb logcat in the Dart process.
2. On trap ... EXIT, dumps the logs to stdout.

Ideally, we'd filter and only show messages relevant to the running app (or test suite). Must haves:

• Messages printed from the Java or Dart applications or test suite
• Uncaught exceptions or asserts from the Java or Dart applications or test suite
• Verification that screenshots have been taken and uploaded to Skia gold (if applicable)
• More status logging (see Impeller OpenGLES (Scenario App) Tests are unstable on CI #143626)

This work is somewhat important, because debugging these tests on CI (and even locally) is non-trivial, and we suspect cases where certain tests are not running, or not taking screenshots consistently (at least on CI). Logging would be one part of feeling more certain that the tests are running as expected.

Log filtering historically has been brittle, so it might be good to have some small tests that verify this keeps working.