Add callback for codec format change.

When creating native audio track, a IAudioTrackCallback will be created
systematically. All callbacks will be cached in Threads and protected by
a lock. Whenever there is a callback event from audio HAL, it will
finally trigger callback to native audio track. Currently, there is only
one callback event, which is codec format change.

Bug: 150301890
Test: manual
Change-Id: I32293627ed923b17dd25f11f0ee0a0c35cd7c01f
diff --git a/media/libaudiohal/impl/StreamHalHidl.h b/media/libaudiohal/impl/StreamHalHidl.h
index f587889..88f8587 100644
--- a/media/libaudiohal/impl/StreamHalHidl.h
+++ b/media/libaudiohal/impl/StreamHalHidl.h
@@ -173,6 +173,11 @@
     void onDrainReady();
     void onError();
 
+    status_t setEventCallback(const sp<StreamOutHalInterfaceEventCallback>& callback) override;
+
+    // Methods used by StreamCodecFormatCallback (HIDL).
+    void onCodecFormatChanged(const std::basic_string<uint8_t>& metadataBs);
+
   private:
     friend class DeviceHalHidl;
     typedef MessageQueue<WriteCommand, hardware::kSynchronizedReadWrite> CommandMQ;
@@ -180,6 +185,7 @@
     typedef MessageQueue<WriteStatus, hardware::kSynchronizedReadWrite> StatusMQ;
 
     wp<StreamOutHalInterfaceCallback> mCallback;
+    wp<StreamOutHalInterfaceEventCallback> mEventCallback;
     sp<IStreamOut> mStream;
     std::unique_ptr<CommandMQ> mCommandMQ;
     std::unique_ptr<DataMQ> mDataMQ;