Adds shuchen@ as the owner for overall IMF.

BUG=N/A
TEST=N/A

Review URL: https://codereview.chromium.org/671343002

Cr-Commit-Position: refs/heads/master@{#301094}

ash/ime/OWNERS

@@ -2,6 +2,7 @@
 mukai@chromium.org
 
 # backup reviewers
+shuchen@chromium.org
 komatsu@chromium.org
 nona@chromium.org
 yukishiino@chromium.org

chromeos/ime/OWNERS

 # primary reviewer
-yukishiino@chromium.org
+shuchen@chromium.org
 
 # backup reviewers
+yukishiino@chromium.org
 komatsu@chromium.org
 nona@chromium.org
 satorux@chromium.org

ui/base/ime/OWNERS

 # primary reviewer.
 yukishiino@chromium.org
+shuchen@chromium.org
 
 # backup reviewers.
 komatsu@chromium.org

ui/views/ime/OWNERS

 # primary reviewer
 yukishiino@chromium.org
+shuchen@chromium.org
 
 # backup reviewers.
 mukai@chromium.org