Android AppRTCDemo: Add slider for changing camera capture quality during call

webrtc/examples/androidapp/res/values/strings.xml

 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="app_name" translatable="no">AppRTC</string>
     <string name="settings_name" translatable="no">AppRTC Settings</string>
     <string name="disconnect_call">Disconnect Call</string>
     <string name="room_names">Room names:</string>
     <string name="room_description">
         Please enter a room name. Room names are shared with everyone, so think
         of something unique and send it to a friend.
     </string>
@@ skipping 28 matching lines @@
     <string name="pref_resolution_key">resolution_preference</string>
     <string name="pref_resolution_title">Video resolution.</string>
     <string name="pref_resolution_dlg">Enter AppRTC local video resolution.</string>
     <string name="pref_resolution_default">Default</string>
 
     <string name="pref_fps_key">fps_preference</string>
     <string name="pref_fps_title">Camera fps.</string>
     <string name="pref_fps_dlg">Enter local camera fps.</string>
     <string name="pref_fps_default">Default</string>
 
+    <string name="pref_capturequalityslider_key">capturequalityslider_preference</string>
+    <string name="pref_capturequalityslider_title">Capture quality slider.</string>
+    <string name="pref_capturequalityslider_dlg">Enable slider for changing capture quality.</string>
+    <string name="pref_capturequalityslider_default">false</string>
+
     <string name="pref_startvideobitrate_key">startvideobitrate_preference</string>
     <string name="pref_startvideobitrate_title">Start video bitrate setting.</string>
     <string name="pref_startvideobitrate_dlg">Start video bitrate setting.</string>
     <string name="pref_startvideobitrate_default">Default</string>
 
     <string name="pref_startvideobitratevalue_key">startvideobitratevalue_preference</string>
     <string name="pref_startvideobitratevalue_title">Video encoder start bitrate.</string>
     <string name="pref_startvideobitratevalue_dlg">Enter video encoder start bitrate in kbps.</string>
     <string name="pref_startvideobitratevalue_default">1000</string>
 
@@ skipping 45 matching lines @@
     <string name="pref_room_server_url_title">Room server URL.</string>
     <string name="pref_room_server_url_dlg">Enter a room server URL.</string>
     <string name="pref_room_server_url_default" translatable="false">https://apprtc.appspot.com</string>
 
     <string name="pref_displayhud_key">displayhud_preference</string>
     <string name="pref_displayhud_title">Display call statistics.</string>
     <string name="pref_displayhud_dlg">Display call statistics.</string>
     <string name="pref_displayhud_default" translatable="false">false</string>
 
 </resources>