chromeos-daisy_skate-chrome-pfq failed for the same issue since this build:
https://uberchromegw.corp.google.com/i/chromeos/builders/daisy_skate-chrome-pfq/builds/5559

The errors look the same as seen on caroline and tricky informational bot.
chromeos-chrome-67.0.3377.0_rc-r1: Copying Chrome tests into /build/daisy_skate/tmp/portage/chromeos-base/chromeos-chrome-67.0.3377.0_rc-r1/work/test_src
chromeos-chrome-67.0.3377.0_rc-r1:  * Installing test targets: jpeg_decode_accelerator_unittest media_unittests sandbox_linux_unittests video_decode_accelerator_unittest video_encode_accelerator_unittest wayland_client_perftests ppapi/examples/video_decode libppapi_tests.so chrome_sandbox
chromeos-chrome-67.0.3377.0_rc-r1: armv7a-cros-linux-gnueabi-strip: '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi/examples/video_decode': No such file
chromeos-chrome-67.0.3377.0_rc-r1: armv7a-cros-linux-gnueabi-strip: '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/libppapi_tests.so': No such file
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/pseudo_locales/fake-bidi.pak': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/lib32': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/lib64': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/mock_nacl_gdb': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_newlib.nmf': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_glibc.nmf': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_newlib_x32.nexe': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_newlib_x64.nexe': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_newlib_arm.nexe': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_glibc_x32.nexe': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_glibc_x64.nexe': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/ppapi_nacl_tests_glibc_arm.nexe': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/test_case.html': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/test_case.html.mock-http-headers': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/test_page.css': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1: cp: cannot stat '/var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/test_url_loader_data': No such file or directory
chromeos-chrome-67.0.3377.0_rc-r1:  * install_test_resources to /build/daisy_skate/tmp/portage/chromeos-base/chromeos-chrome-67.0.3377.0_rc-r1/work/test_src
chromeos-chrome-67.0.3377.0_rc-r1: rsync: link_stat "/home/chrome-bot/chrome_root/src/chrome/test/functional" failed: No such file or directory (2)
chromeos-chrome-67.0.3377.0_rc-r1: rsync: link_stat "/home/chrome-bot/chrome_root/src/content/common/gpu/testdata" failed: No such file or directory (2)
chromeos-chrome-67.0.3377.0_rc-r1: rsync: link_stat "/home/chrome-bot/chrome_root/src/third_party/accessibility-developer-tools/gen/axs_testing.js" failed: No such file or directory (2)
chromeos-chrome-67.0.3377.0_rc-r1: rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1178) [sender=3.1.2]

peach_pit-chrome-pfq, peppy-chrome-pfq, tricky-chrome-pfq, tricky-chrome-pfq,veyron_rialto-chrome-pfq all failed building package for the same issue.

+bbudge +raymes

all the files in #1 that cannot stat are in ppapi/test/. do either of you have any ideas what might be causing this?

Digging in the log, found this:
chromeos-chrome-67.0.3377.0_rc-r1:  * Installing tests
...
chromeos-chrome-67.0.3377.0_rc-r1: /var/cache/chromeos-chrome/chrome-src-internal/src/out_daisy_skate/Release/libwidevinecdmadapter.so does not exist and is required.
chromeos-chrome-67.0.3377.0_rc-r1: You can bypass this error with --sloppy.
chromeos-chrome-67.0.3377.0_rc-r1: Aborting copy...
chromeos-chrome-67.0.3377.0_rc-r1:  * ERROR: chromeos-base/chromeos-chrome-67.0.3377.0_rc-r1::chromiumos failed (install phase):

It looks like libwidevinecdmadapter.so is required but not found, therefore, the installation process is aborted. 

The following cl removed libwidevinecdmadapter.so, but didn't update the install script, therefore, causing this failure.
https://chromium-review.googlesource.com/c/chromium/src/+/957868

xhwang@, would you please take a look how to fix the problem?

bots are green after the fix landed:

https://uberchromegw.corp.google.com/i/chromeos.chrome/builders/caroline-tot-chrome-pfq-informational/builds/1265