Android: Capture more tombstones in instrumentation tests

When chrome_public_smoke_test has a crash, our test runner does not
notice and so does not collect tombstones.

This changes the "are there tombstones" logic to look for a tombstone
message in logcat rather than looking to see if any tests crashed.

Bug: 1117540
Change-Id: Ic0594f0d8dcb2cb8c7280ade9d8d5133c890614f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363075
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799490}

build/android/pylib/local/device/local_device_instrumentation_test_run.py

@@ -783,24 +783,30 @@ def stop_chrome_proxy():
       logging.debug('raw output from %s:', test_display_name)
       for l in output:
         logging.debug('  %s', l)
+
     if self._test_instance.store_tombstones:
-      tombstones_url = None
-      for result in results:
-        if result.GetType() == base_test_result.ResultType.CRASH:
-          if not tombstones_url:
-            resolved_tombstones = tombstones.ResolveTombstones(
-                device,
-                resolve_all_tombstones=True,
-                include_stack_symbols=False,
-                wipe_tombstones=True,
-                tombstone_symbolizer=self._test_instance.symbolizer)
-            tombstone_filename = 'tombstones_%s_%s' % (
-                time.strftime('%Y%m%dT%H%M%S-UTC', time.gmtime()),
-                device.serial)
-            with self._env.output_manager.ArchivedTempfile(
-                tombstone_filename, 'tombstones') as tombstone_file:
-              tombstone_file.write('\n'.join(resolved_tombstones))
+      resolved_tombstones = tombstones.ResolveTombstones(
+          device,
+          resolve_all_tombstones=True,
+          include_stack_symbols=False,
+          wipe_tombstones=True,
+          tombstone_symbolizer=self._test_instance.symbolizer)
+      if resolved_tombstones:
+        tombstone_filename = 'tombstones_%s_%s' % (time.strftime(
+            '%Y%m%dT%H%M%S-UTC', time.gmtime()), device.serial)
+        with self._env.output_manager.ArchivedTempfile(
+            tombstone_filename, 'tombstones') as tombstone_file:
+          tombstone_file.write('\n'.join(resolved_tombstones))
+
+        # Associate tombstones with first crashing test.
+        for result in results:
+          if result.GetType() == base_test_result.ResultType.CRASH:
             result.SetLink('tombstones', tombstone_file.Link())
+            break
+        else:
+          # We don't always detect crashes correctly. In this case,
+          # associate with the first test.
+          results[0].SetLink('tombstones', tombstone_file.Link())
     return results, None
 
   def _GetTestsFromRunner(self):