aaudio: cache framesPerBurst and capacity

These do not change after opening the stream so we can
simply return a stored value and avoid querying the device.

Test: atest AAudioTests
Change-Id: I7a66c12bd695fd732194ff0a14ac9c8d9cacf923
diff --git a/media/libaaudio/src/legacy/AudioStreamTrack.h b/media/libaaudio/src/legacy/AudioStreamTrack.h
index 6334f66..5a8fb39 100644
--- a/media/libaaudio/src/legacy/AudioStreamTrack.h
+++ b/media/libaaudio/src/legacy/AudioStreamTrack.h
@@ -69,8 +69,6 @@
 
     aaudio_result_t setBufferSize(int32_t requestedFrames) override;
     int32_t getBufferSize() const override;
-    int32_t getBufferCapacity() const override;
-    int32_t getFramesPerBurst()const  override;
     int32_t getXRunCount() const override;
 
     int64_t getFramesRead() override;
@@ -96,6 +94,11 @@
             const android::media::VolumeShaper::Operation& operation) override;
 #endif
 
+protected:
+
+    int32_t getFramesPerBurstFromDevice() const override;
+    int32_t getBufferCapacityFromDevice() const override;
+
 private:
 
     android::sp<android::AudioTrack> mAudioTrack;
@@ -105,10 +108,6 @@
 
     // TODO add 64-bit position reporting to AudioTrack and use it.
     aaudio_wrapping_frames_t         mPositionWhenPausing = 0;
-
-    // initial AudioTrack frame count and notification period
-    int32_t mInitialBufferCapacity = 0;
-    int32_t mInitialFramesPerBurst = 0;
 };
 
 } /* namespace aaudio */