I noticed this error recently: 
https://build.chromium.org/p/chromium.android/builders/Android%20Cronet%20ARMv6%20Builder/builds/2742/steps/compile/logs/stdio

compile passes, but the goma info upload fails like this:
Killing compiler proxy.
compiler proxy status: http://127.0.0.1:8088 quit!

/ b / b u i l d / s c r i p t s / s l a v e / . r e c i p e _ d e p s / d e p o t _ t o o l s / g s u t i l . p y cp file:///tmp/tmp9ARpzo gs://chrome-goma-log/2016/08/03/build69-b1/compiler_proxy-subproc.build69-b1.chrome-bot.log.INFO.20160802-232756.12588.gz
Traceback (most recent call last):
  File "/b/build/scripts/slave/compile.py", line 540, in <module>
    sys.exit(real_main())
  File "/b/build/scripts/slave/compile.py", line 534, in real_main
    goma_teardown(options, env, exit_status, goma_cloudtail)
  File "/b/build/scripts/slave/compile.py", line 211, in goma_teardown
    StopGomaClientAndUploadInfo(options, env, exit_status)
  File "/b/build/scripts/slave/compile.py", line 100, in StopGomaClientAndUploadInfo
    goma_utils.UploadGomaCompilerProxyInfo(override_gsutil=override_gsutil)
  File "/b/build/scripts/slave/goma_utils.py", line 121, in UploadGomaCompilerProxyInfo
    override_gsutil=override_gsutil)
  File "/b/build/scripts/slave/goma_utils.py", line 108, in UploadToGomaLogGS
    slave_utils.GSUtilCopy(temp.name, gs_path, override_gsutil=override_gsutil)
  File "/b/build/scripts/slave/slave_utils.py", line 423, in GSUtilCopy
    return chromium_utils.RunCommand(command)
  File "/b/build/scripts/common/chromium_utils.py", line 1022, in RunCommand
    bufsize=0, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
    raise child_exception
OSError: [Errno 13] Permission denied