aaudio: set default buffer size to capacity/2

A recent change in master caused the default buffer size to be zero. ag/9499599
That caused a CTS failure.
This change restores the behavior of Q.

Bug: 143308870
Test: atest CtsNativeMediaAAudioTestCases
Change-Id: Id70b0c53e80531c3ea491b56b8fc107ca5ab6e51
diff --git a/media/libaaudio/src/client/AudioStreamInternal.cpp b/media/libaaudio/src/client/AudioStreamInternal.cpp
index 6614e5e..7481daa 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternal.cpp
@@ -250,6 +250,8 @@
         mTimeOffsetNanos = offsetMicros * AAUDIO_NANOS_PER_MICROSECOND;
     }
 
+    setBufferSize(capacity / 2); // Default buffer size to match Q
+
     setState(AAUDIO_STREAM_STATE_OPEN);
 
     return result;
@@ -739,6 +741,7 @@
     adjustedFrames = std::min(actualFrames, adjustedFrames);
 
     mBufferSizeInFrames = adjustedFrames;
+    ALOGV("%s(%d) returns %d", __func__, requestedFrames, adjustedFrames);
     return (aaudio_result_t) adjustedFrames;
 }