Show Android picker apps in CrOS File selector when it is opened from an Android app

Design doc : go/arc-file-picker-get-content
             (See "Implementation details" -> "File Manager")
Demo video : go/arc-file-picker-get-content-demo

BUG=b:130204519
TEST=browser_tests --gtest_filter="FileManagerJsTest.NavigationListModelTest"

Change-Id: I1f9e89b456186a891d6ec94bb6869b77cb1afafe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1547627
Reviewed-by: Sam McNally <sammc@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Commit-Queue: Satoshi Niwa <niwa@chromium.org>
Auto-Submit: Satoshi Niwa <niwa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#655171}