aaudio: Fix getFramesWritten() for callback mode.

Plus other small fixes for CTS and cleanup

Bug: 37910599
Test: test_aaudio.cpp
Change-Id: I65a23daf99e9de857d3ce9fd12e9f11c614e298e
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/media/libaaudio/src/client/AudioStreamInternal.h b/media/libaaudio/src/client/AudioStreamInternal.h
index e550ba3..18a55cf 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.h
+++ b/media/libaaudio/src/client/AudioStreamInternal.h
@@ -77,6 +77,7 @@
     int32_t getFramesPerBurst() const override;
 
     int64_t getFramesRead() override;
+    int64_t getFramesWritten() override;
 
     int32_t getXRunCount() const override {
         return mXRunCount;