android: pythonthreefication kicks to stack.py

These changes made the stack tool work for me without hanging
and crashing in Python3.

I did not inspect the surrounding code and did not test with other tools
from bin/, YMMV.

Also I was confused with these things done by the tool:

1. Copying its input to the output before processing it. :butwhymeme:
   - removed this printing

2. Ignoring EOF
   - change it to stop processing input when encountering EOF (i.e.
     pressing Ctrl+D ends the session quietly)

3. Waiting for a line "not looking like backtrace" to start symbolizing
   - clarified this in the welcome message

      # Now paste a crash from logcat.

Bug: None
Test: out/AndroidRelease/bin/trichrome_chrome_google_bundle stack \
Change-Id: I36431ae7c46252aae9e21122ce931f7111b41d22
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3190107
Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/main@{#926227}
NOKEYCHECK=True
GitOrigin-RevId: 86775be5a579b53a01d09d47d82b666aea9b251a
2 files changed
tree: df209fc194686ec2e8b92ef5b46e5482e64542b0
  1. development/
  2. DIR_METADATA
  3. LICENSE
  4. OWNERS
  5. README.chromium