Revert "chromeos: Move files in //ash/common to //ash, part 3"

Landing this right after the M58 branch will complicate backports. I'm
going to land it right before the M59 branch.

This reverts commit 654b40da8d742dffec55c07907136d4c08c49c9e.

Original description:
Now that mustash can use standard aura windows we don't need the ash/aura
vs. ash/mus vs. ash/common distinction. Eliminate //ash/common. Also move
files in //ash/common/system/chromeos out to //ash/system because ash only
compiles on chromeos these days.

Part 3 the rest of //ash/common into //ash. The CQ cannot move all the
files at once, see https://codereview.chromium.org/2734653002/

BUG=690096
TEST=compiles, ash_unittests
[email protected]
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2729363002
Cr-Original-Commit-Position: refs/heads/master@{#454793}
Committed: https://chromium.googlesource.com/chromium/src/+/654b40da8d742dffec55c07907136d4c08c49c9e
Review-Url: https://codereview.chromium.org/2734733002 .
Cr-Commit-Position: refs/heads/master@{#454797}
diff --git a/WATCHLISTS b/WATCHLISTS
index 7ccf843f..0b141fe 100644
--- a/WATCHLISTS
+++ b/WATCHLISTS
@@ -1120,7 +1120,7 @@
       'filepath': 'ui/keyboard/'\
                   '|chrome/test/data/chromeos/virtual_keyboard/'\
                   '|extensions/browser/api/virtual_keyboard_private/'\
-                  '|ash/system/virtual_keyboard/'\
+                  '|ash/common/system/chromeos/virtual_keyboard/'\
                   '|ash/virtual_keyboard',
     },
     'virtual_reality': {