Flag for FGS audio control

Flag controls ability for apps to request
audio focus gain, requires app to be
foreground or FGS or delegate for mic / call /
audio playback / camera service type.

Flag: android.media.audio.foreground_audio_control
Bug: 296232417
Test: adb shell device_config put media_audio android.media.audio.foreground_audio_control true ;\
      atest CtsAppTestCases:android.app.cts.ActivityManagerFgsBgStartTest
Change-Id: Ic6c240e2ba8156220f7af7cf8c6a405384beca64
diff --git a/media/audio/aconfig/audio_framework.aconfig b/media/audio/aconfig/audio_framework.aconfig
index 34c026a..432df3c 100644
--- a/media/audio/aconfig/audio_framework.aconfig
+++ b/media/audio/aconfig/audio_framework.aconfig
@@ -30,6 +30,15 @@
     bug: "316414750"
 }
 
+flag {
+    name: "foreground_audio_control"
+    namespace: "media_audio"
+    description:
+        "Audio focus gain requires FGS or delegation to "
+	"take effect"
+    bug: "296232417"
+}
+
 # TODO remove
 flag {
     name: "focus_freeze_test_api"