GM: add --writeChecksumBasedFilenames option

gm/tests/run.sh

 #!/bin/bash
 
 # Self-tests for gm, based on tools/tests/run.sh
 #
 # These tests are run by the Skia_PerCommit_House_Keeping bot at every commit,
 # so make sure that they still pass when you make changes to gm!
 #
 # To generate new baselines when gm behavior changes, run gm/tests/rebaseline.sh
 #
 # TODO: because this is written as a shell script (instead of, say, Python)
@@ skipping 198 matching lines @@
 
 # Confirm that IntentionallySkipped tests are recorded as such.
 gm_test "--verbose --hierarchy --match selftest1 selftest2 $CONFIGS" "$GM_OUTPUTS/intentionally-skipped-tests"
 
 # Ignore some error types (including ExpectationsMismatch)
 gm_test "--ignoreErrorTypes ExpectationsMismatch NoGpuContext --verbose --hierarchy --match selftest1 $CONFIGS -r $GM_INPUTS/json/different-pixels.json" "$GM_OUTPUTS/ignore-expectations-mismatch"
 
 # Test non-hierarchical mode.
 gm_test "--verbose --match selftest1 $CONFIGS -r $GM_INPUTS/json/different-pixels-no-hierarchy.json" "$GM_OUTPUTS/no-hierarchy"
 
+# Try writing out actual images using checksum-based filenames, like we do when
+# uploading to Google Storage.
+gm_test "--verbose --writeChecksumBasedFilenames --match selftest1 $CONFIGS -r $GM_INPUTS/json/different-pixels-no-hierarchy.json" "$GM_OUTPUTS/checksum-based-filenames"
+
 # Exercise display_json_results.py
 PASSING_CASES="compared-against-identical-bytes-json compared-against-identical-pixels-json"
 FAILING_CASES="compared-against-different-pixels-json"
 for CASE in $PASSING_CASES; do
   assert_passes "python gm/display_json_results.py $GM_OUTPUTS/$CASE/$OUTPUT_EXPECTED_SUBDIR/json-summary.txt"
 done
 for CASE in $FAILING_CASES; do
   assert_fails "python gm/display_json_results.py $GM_OUTPUTS/$CASE/$OUTPUT_EXPECTED_SUBDIR/json-summary.txt"
 done
 
 if [ $ENCOUNTERED_ANY_ERRORS == 0 ]; then
   echo "All tests passed."
   exit 0
 else
   exit 1
 fi