Renames example_wm to mash_wm

Also, fixes wm_apptest and adds to list of tests to run.

BUG=none
TEST=none
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Review URL: https://codereview.chromium.org/1478813002

Cr-Commit-Position: refs/heads/master@{#361801}
6 files changed