Update OWNERS, README and markdown docs wrt //components/browser_ui

Bug: 1034609
Change-Id: Ie32dc7e7a92f8286a5ab3357cfc9a1cb51f2d4ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1972169Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Auto-Submit: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726413}

chrome/browser/ui/android/widget/README

+Note: this directory is in the process of being migrated to
+//components/browser_ui/widget/android. Consider adding new code there instead
+of here. If your code is specific to Chrome (e.g. references tabs, omnibox,
+etc), it likely does not belong in widget.

components/browser_ui/OWNERS

+tedchoc@chromium.org
+twellington@chromium.org
+
+# TEAM: chrome-android-app@chromium.org
+# COMPONENT: UI>Browser>Mobile
+# OS: Android

components/browser_ui/README

+The browser_ui component consists of modularized build targets for common
+UI elements that are useful for building a browser. Currently it contains
+Android code that is used by WebLayer and Chrome.

components/browser_ui/widget/android/OWNERS

+twellington@chromium.org

components/browser_ui/widget/android/README

+The org.chromium.components.browser_ui.widget package contains generally useful
+UI utilities with no feature-specific code or dependencies.
+
+TODO(crbug.com/1030785): Most or all of org.chromium.chrome.browser.ui.widget
+should be relocated to this package.

docs/ui/android/overview.md

@@ -22,7 +22,7 @@ Text should be styled with a pre-defined text appearance from [//ui/android/java
 
 The Chromium code base contains a number of wrappers around Android classes (to smooth over bugs or save on binary size) and many UI widgets that provide Chrome-specific behavior and/or styling.
 
-These can be found in [//chrome/browser/ui/android/widget/](/chrome/browser/ui/android/widget/), [//ui/android/](/ui/android/), and [//chrome/android/java/src/org/chromium/chrome/browser/widget/](/chrome/android/java/src/org/chromium/chrome/browser/widget/). There is an ongoing effort to consolidate all widgets in //chrome/browser/ui/android/widget/.
+These can be found in [//components/browser_ui/widget/android/](/components/browser_ui/widget/android/), [//chrome/browser/ui/android/widget/](/chrome/browser/ui/android/widget/), [//ui/android/](/ui/android/), and [//chrome/android/java/src/org/chromium/chrome/browser/widget/](/chrome/android/java/src/org/chromium/chrome/browser/widget/). There is an ongoing effort to consolidate all widgets in //components/browser_ui/widget/android.
 
 ## MVC