chromium/components/browser_ui/photo_picker/android/java/res/drawable/photo_picker_seekbar_track.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
Copyright 2020 The Chromium Authors
Use of this source code is governed by a BSD-style license that can be
found in the LICENSE file.
-->

<!-- A SeekBar track is composed of up to three components:

1) A line for showing playback progress (android:id/progress).
2) A line for showing buffering progress (android:id/secondaryProgress).
3) A background element (@android:id/background), which frames the playback and buffering lines,
   thereby indicating how much remains of playback and/or buffering.

The buffering progress line (item 2 above) is omitted here, because it is not needed due to the fact
that the videos are all readily available on disk and don't need to be downloaded. -->
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@android:id/background"
        android:gravity="center_vertical|fill_horizontal">
        <shape android:shape="rectangle">
            <corners android:radius="@dimen/photo_picker_seek_bar_edge_radius" />
            <size android:height="@dimen/photo_picker_seek_bar_thickness" />
            <gradient
                android:angle="90"
                android:startColor="@color/modern_grey_500"
                android:endColor="@color/modern_grey_500" />
        </shape>
    </item>

    <item android:id="@android:id/progress"
        android:gravity="center_vertical|fill_horizontal">
        <clip>
            <shape android:shape="rectangle">
                <corners android:radius="@dimen/photo_picker_seek_bar_edge_radius" />
                <size android:height="@dimen/photo_picker_seek_bar_thickness" />
                <gradient
                    android:angle="90"
                    android:startColor="@color/default_primary_color"
                    android:endColor="@color/default_primary_color" />
            </shape>
        </clip>
    </item>
</layer-list>