Add more logging in DoLaunchChildTestProcess().

When it calls ReadFileToString() and fails, log the name of the file it
is trying to read.

BUG=826408

Change-Id: I546977b985c71cbd631820e7d7950b7f7449faba
Reviewed-on: https://chromium-review.googlesource.com/1024743
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553188}

CrOS-Libchrome-Original-Commit: e0ed6f1d52bd888c99af8fa6038e627c1a300dd4
1 file changed
tree: 48a5d8f2a013ee0e1f2f5b82ea3034e4a5e38157
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/