Capture system logs when running host-side tests on CrOS DUTs.

Bug: 608034
Change-Id: Iec72254dd2949c329be60980f27dd7c940b26fcc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1717158
Reviewed-by: Dirk Pranke <[email protected]>
Commit-Queue: Ben Pastene <[email protected]>
Cr-Commit-Position: refs/heads/master@{#680869}
diff --git a/tools/mb/mb.py b/tools/mb/mb.py
index a5120181..ba3af5a 100755
--- a/tools/mb/mb.py
+++ b/tools/mb/mb.py
@@ -1296,7 +1296,10 @@
       # If we're testing a CrOS simplechrome build, assume we need to prepare a
       # DUT for testing. So prepend the command to run with the test wrapper.
       if is_simplechrome:
-        cmdline = [os.path.join('bin', 'cros_test_wrapper')]
+        cmdline = [
+            os.path.join('bin', 'cros_test_wrapper'),
+            '--logs-dir=${ISOLATED_OUTDIR}',
+        ]
       cmdline += [
           '../../testing/test_env.py',
           '../../' + self.ToSrcRelPath(isolate_map[target]['script'])