audio policy: add binder calls for audio source control

Add binder methods to IAudioPolicyService to control activity
of external audio sources (e.g FM tuner).

Change-Id: I2008308a6a996baeae502b68a790d87281efe2ff
diff --git a/services/audiopolicy/managerdefault/AudioPolicyManager.h b/services/audiopolicy/managerdefault/AudioPolicyManager.h
index fe6b986..146a7af 100644
--- a/services/audiopolicy/managerdefault/AudioPolicyManager.h
+++ b/services/audiopolicy/managerdefault/AudioPolicyManager.h
@@ -220,6 +220,11 @@
         virtual status_t registerPolicyMixes(Vector<AudioMix> mixes);
         virtual status_t unregisterPolicyMixes(Vector<AudioMix> mixes);
 
+        virtual status_t startAudioSource(const struct audio_port_config *source,
+                                          const audio_attributes_t *attributes,
+                                          audio_io_handle_t *handle);
+        virtual status_t stopAudioSource(audio_io_handle_t handle);
+
         // Audio policy configuration file parsing (audio_policy.conf)
         // TODO candidates to be moved to ConfigParsingUtils
                 void defaultAudioPolicyConfig(void);