AudioPolicyManager: return output for audio attributes

In AudioPolicyManager, support querying an output
 or playback strategy for audio attributes,
 instead of a stream type,
In AudioTrack creation, use the output returned
 for the track's attributes.

Change-Id: I0fef05845ba676404775e2e338c10e6a96237268
diff --git a/include/media/IAudioPolicyService.h b/include/media/IAudioPolicyService.h
index d422aa3..959e4c3 100644
--- a/include/media/IAudioPolicyService.h
+++ b/include/media/IAudioPolicyService.h
@@ -56,6 +56,12 @@
                                         audio_channel_mask_t channelMask = 0,
                                         audio_output_flags_t flags = AUDIO_OUTPUT_FLAG_NONE,
                                         const audio_offload_info_t *offloadInfo = NULL) = 0;
+    virtual audio_io_handle_t getOutputForAttr(const audio_attributes_t *attr,
+                                            uint32_t samplingRate = 0,
+                                            audio_format_t format = AUDIO_FORMAT_DEFAULT,
+                                            audio_channel_mask_t channelMask = 0,
+                                            audio_output_flags_t flags = AUDIO_OUTPUT_FLAG_NONE,
+                                            const audio_offload_info_t *offloadInfo = NULL) = 0;
     virtual status_t startOutput(audio_io_handle_t output,
                                  audio_stream_type_t stream,
                                  int session = 0) = 0;