Support querying active record sources

Add support for querying whether there is currently a recording
 underway from the specified audio source.

Bug 7314859

Change-Id: I986b231a10ffd368b08ec2f9c7f348d28eaeb892
diff --git a/services/audioflinger/AudioPolicyService.h b/services/audioflinger/AudioPolicyService.h
index a086734..63f9549 100644
--- a/services/audioflinger/AudioPolicyService.h
+++ b/services/audioflinger/AudioPolicyService.h
@@ -104,6 +104,7 @@
     virtual status_t unregisterEffect(int id);
     virtual status_t setEffectEnabled(int id, bool enabled);
     virtual bool isStreamActive(audio_stream_type_t stream, uint32_t inPastMs = 0) const;
+    virtual bool isSourceActive(audio_source_t source) const;
 
     virtual status_t queryDefaultPreProcessing(int audioSession,
                                               effect_descriptor_t *descriptors,