OS: Linux

What steps will reproduce the problem?
(1)Running the mojo/validation.html test from https://codereview.chromium.org/2745293005/#ps840001

What is the expected result?
The test build generates a list of all files in the mojo/public/interfaces/bindings/tests/data/validation directory, and places that list in /gen/layout_test_data/validation_files.txt.  It also copies all files from mojo/public/interfaces/bindings/tests/data/validation to /gen/layout_test_data/validation
The test should be able to fetch these files to run the tests on their contents

What happens instead?

The test passes when run on a local machine, but fails when run on the try server.  The /gen/ directory that the file is copied to is different than the /gen/ directory that the file is being fetched from during the linux tests.  This passes on all other systems.  

On the linux_chromium_rel_ng test, the file is being copied to /b/c/b/linux/src/out/Release/gen/layout_test_data/validation_files.txt
but fetched from 
file:///b/s/w/ir/out/Release/gen/layout_test_data/validation_files.txt
and therefore the file is not found and the test fails.