OWNERS files updated with latest COMPONENT and TEAMS.

This is CL is generated by a script. Data is pulled from
review conducted in Q2 2019. See https://tinyurl.com/yxau5sc4
for context.

Bug: 977050
Change-Id: I08fdb07a9cc05d6f14e52a86236549be7f89eadc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1700852Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Eric Foo <efoo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#681552}

ash/system/accessibility/OWNERS

+# COMPONENT: UI>Accessibility
+# TEAM: chromium-accessibility@chromium.org

ash/system/keyboard_brightness/OWNERS

+# COMPONENT: OS>Systems>Input>Keyboard

ash/system/screen_security/OWNERS

+# COMPONENT: UI>Shell>LockScreen

ash/system/virtual_keyboard/OWNERS

+# COMPONENT: UI>Input>VirtualKeyboard

components/onc/OWNERS

@@ -2,3 +2,4 @@ armansito@chromium.org
 gauravsh@chromium.org
 gspencer@chromium.org
 stevenjb@chromium.org
+# COMPONENT: UI>Shell>Networking

components/proxy_config/OWNERS

 stevenjb@chromium.org
+# COMPONENT: UI>Shell>Networking

ui/chromeos/OWNERS

@@ -3,3 +3,4 @@ oshima@chromium.org
 stevenjb@chromium.org
 
 per-file file_manager_strings.grdp=*
+# COMPONENT: UI