It seems that the PFQs are failing because of a failure in building chromeos-chrome.

Here's a snippet of the failure.

chromeos-chrome-51.0.2665.0_rc-r1: Copying Chrome tests into /build/x86-generic/tmp/portage/chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1/work/test_src
chromeos-chrome-51.0.2665.0_rc-r1:  * Installing test targets: media_unittests sandbox_linux_unittests ppapi_example_video_decode video_decode_accelerator_unittest video_encode_accelerator_unittest libppapi_tests.so chrome_sandbox
chromeos-chrome-51.0.2665.0_rc-r1: i686-pc-linux-gnu-strip: '/var/cache/chromeos-chrome/chrome-src/src/out_x86-generic/Release/ppapi_example_video_decode': No such file
chromeos-chrome-51.0.2665.0_rc-r1:  * ERROR: chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1::chromiumos failed (compile phase):
chromeos-chrome-51.0.2665.0_rc-r1:  *   (no error message)
chromeos-chrome-51.0.2665.0_rc-r1:  * 
chromeos-chrome-51.0.2665.0_rc-r1:  * Call stack:
chromeos-chrome-51.0.2665.0_rc-r1:  *     ebuild.sh, line   93:  Called src_compile
chromeos-chrome-51.0.2665.0_rc-r1:  *   environment, line 3691:  Called install_chrome_test_resources '/build/x86-generic/tmp/portage/chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1/work/test_src'
chromeos-chrome-51.0.2665.0_rc-r1:  *   environment, line 2495:  Called test_strip_install '/var/cache/chromeos-chrome/chrome-src/src/out_x86-generic/Release' '/build/x86-generic/tmp/portage/chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1/work/test_src/out/Release' 'media_unittests' 'sandbox_linux_unittests' 'ppapi_example_video_decode' 'video_decode_accelerator_unittest' 'video_encode_accelerator_unittest' 'libppapi_tests.so' 'chrome_sandbox'
chromeos-chrome-51.0.2665.0_rc-r1:  *   environment, line 4534:  Called die
chromeos-chrome-51.0.2665.0_rc-r1:  * The specific snippet of code:
chromeos-chrome-51.0.2665.0_rc-r1:  *           $(tc-getSTRIP) --strip-debug --keep-file-symbols "${from}"/${f} -o "${dest}/$(basename ${f})" || die;
chromeos-chrome-51.0.2665.0_rc-r1:  * 
chromeos-chrome-51.0.2665.0_rc-r1:  * If you need support, post the output of `emerge --info '=chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1::chromiumos'`,
chromeos-chrome-51.0.2665.0_rc-r1:  * the complete build log and the output of `emerge -pqv '=chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1::chromiumos'`.
chromeos-chrome-51.0.2665.0_rc-r1:  * The complete build log is located at '/build/x86-generic/tmp/portage/logs/chromeos-base:chromeos-chrome-51.0.2665.0_rc-r1:20160303-141917.log'.
chromeos-chrome-51.0.2665.0_rc-r1:  * For convenience, a symlink to the build log is located at '/build/x86-generic/tmp/portage/chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1/temp/build.log'.
chromeos-chrome-51.0.2665.0_rc-r1:  * The ebuild environment file is located at '/build/x86-generic/tmp/portage/chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1/temp/environment'.
chromeos-chrome-51.0.2665.0_rc-r1:  * Working directory: '/home/chrome-bot/chrome_root/src'
chromeos-chrome-51.0.2665.0_rc-r1:  * S: '/build/x86-generic/tmp/portage/chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1/work/chromeos-chrome-51.0.2665.0_rc'
chromeos-chrome-51.0.2665.0_rc-r1: >>> Failed to emerge chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1 for /build/x86-generic/, Log file:
chromeos-chrome-51.0.2665.0_rc-r1: >>>  '/build/x86-generic/tmp/portage/logs/chromeos-base:chromeos-chrome-51.0.2665.0_rc-r1:20160303-141917.log'
chromeos-chrome-51.0.2665.0_rc-r1: 
chromeos-chrome-51.0.2665.0_rc-r1:  * Messages for package chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1 merged to /build/x86-generic/:
chromeos-chrome-51.0.2665.0_rc-r1: 
chromeos-chrome-51.0.2665.0_rc-r1:  * CHROME_ORIGIN VALUE is LOCAL_SOURCE
chromeos-chrome-51.0.2665.0_rc-r1:  * /home/chrome-bot/chrome_root should be set here properly
chromeos-chrome-51.0.2665.0_rc-r1:  * ERROR: chromeos-base/chromeos-chrome-51.0.2665.0_rc-r1::chromiumos failed (compile phase):

Assigning to current gardener.

Is this similar to chromium:584722? I don't think so.