Updater owners refactoring.

 - guidance is that owners should be committers, so removed mila for now.
 - linked Android and iOS Omaha clients to updater ownership.
 - salute to cpu@, but probably it is time to remove.

Change-Id: I8beda0126d99a31b141c0f86bae6716e0c46446f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419031Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Sorin Jianu <sorin@chromium.org>
Commit-Queue: Joshua Pawlicki <waffles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808353}

chrome/android/java/src/org/chromium/chrome/browser/omaha/OWNERS

+file://chrome/updater/OWNERS
+
 nyquist@chromium.org
-sorin@chromium.org
-waffles@chromium.org
+
+# COMPONENT: Internals>Installer
+# TEAM: chrome-updates-dev@chromium.org
+# OS: Android

chrome/updater/OWNERS

 ganesh@chromium.org
-milagreen@chromium.org
 sorin@chromium.org
 waffles@chromium.org
+
+# COMPONENT: Internals>Updater
+# TEAM: chrome-updates-dev@chromium.org

components/update_client/OWNERS

-cpu@chromium.org
 sorin@chromium.org
 waffles@chromium.org
 

ios/chrome/browser/omaha/OWNERS

+file://chrome/updater/OWNERS
+
+# For iOS / obj-C specific issues:
 rohitrao@chromium.org
 
-# TEAM: ios-directory-owners@chromium.org
+# COMPONENT: Internals>Installer
+# TEAM: chrome-updates-dev@chromium.org
 # OS: iOS