GitLab

 - remove media_inport_handler_unittest.html
 - add BUILD rules to auto-generate and compile this unittest
 - define mockChrome, install it during the unittest
 - remove unused unittest vars and JS auto-format
 - document test fixtures and test helpers
 - fix Closure compile errors (there were lots).

No change in test behavior, no new tests.

Bug: 907970
Change-Id: Id90b4b1eaf84764521fb0d77aa2c29ff56db7c07
Reviewed-on: https://chromium-review.googlesource.com/c/1356728
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612997}