There's something fishy going on when running https://code.google.com/p/chromium/codesearch#chromium/src/chrome/test/data/safe_browsing/dmg/generate_test_data.sh at https://code.google.com/p/chromium/codesearch#chromium/src/chrome/chrome_tests_unit.gypi&l=2775

At least two times recently, the Mac clobber builder has failed with an error like this:

[31795/31795] STAMP obj/build/all_and_dmg.actions_depends.stamp

/b/build/scripts/slave/.recipe_deps/depot_tools/ninja -C /b/build/slave/Mac/build/src/out/Release all chrome -j80 -d explain
ninja: Entering directory `/b/build/slave/Mac/build/src/out/Release'
ninja explain: output test_data/chrome/safe_browsing_dmg/mach_o_in_dmg.dmg doesn't exist
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDBZ_GPTSPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDBZ_NONE.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDBZ_SPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDCO_GPTSPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDCO_NONE.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDCO_SPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDRO_GPTSPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDRO_NONE.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDRO_SPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDRW_GPTSPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDRW_NONE.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDRW_SPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDSP_GPTSPUD.sparseimage is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDSP_NONE.sparseimage is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDSP_SPUD.sparseimage is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDTO_GPTSPUD.cdr is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDTO_NONE.cdr is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDTO_SPUD.cdr is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDZO_GPTSPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDZO_NONE.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UDZO_SPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UFBI_GPTSPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UFBI_NONE.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/dmg_UFBI_SPUD.dmg is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/hfs_plus.img is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/hfsx_case_sensitive.img is dirty
ninja explain: test_data/chrome/safe_browsing_dmg/mach_o_in_dmg.dmg is dirty
[1/2] ACTION unit_tests: Generate safe_browsing DMG test data_a2c47054a61484e399e2bc1586312785
[2/2] STAMP obj/chrome/unit_tests.actions_rules_copies.stamp
Failing build because ninja reported work to do.
This means that after completing a compile, another was run and
it resulted in still having work to do (that is, a no-op build
wasn't a no-op). Consult the first "ninja explain:" line for a
likely culprit.

Logs:
https://build.chromium.org/p/chromium/builders/Mac/builds/14195/steps/compile/logs/stdio
https://build.chromium.org/p/chromium/builders/Mac/builds/14239/steps/compile/logs/stdio

This should be investigated as it leads to unnecessary tree closures.