aaudio: initialize the callback buffer

This can prevent some loud noises during unit tests.

Also use std::unique_ptr

Bug: 154342174
Test: libaaudio/tests/test_various.cpp
Change-Id: I1c1dc0f4a6a29cf7d7a656392a81a325847de22d
diff --git a/media/libaaudio/src/client/AudioStreamInternalCapture.cpp b/media/libaaudio/src/client/AudioStreamInternalCapture.cpp
index 9684ee4..32cf368 100644
--- a/media/libaaudio/src/client/AudioStreamInternalCapture.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternalCapture.cpp
@@ -243,7 +243,7 @@
         int64_t timeoutNanos = calculateReasonableTimeout(mCallbackFrames);
 
         // This is a BLOCKING READ!
-        result = read(mCallbackBuffer, mCallbackFrames, timeoutNanos);
+        result = read(mCallbackBuffer.get(), mCallbackFrames, timeoutNanos);
         if ((result != mCallbackFrames)) {
             ALOGE("callbackLoop: read() returned %d", result);
             if (result >= 0) {
@@ -255,7 +255,7 @@
         }
 
         // Call application using the AAudio callback interface.
-        callbackResult = maybeCallDataCallback(mCallbackBuffer, mCallbackFrames);
+        callbackResult = maybeCallDataCallback(mCallbackBuffer.get(), mCallbackFrames);
 
         if (callbackResult == AAUDIO_CALLBACK_RESULT_STOP) {
             ALOGD("%s(): callback returned AAUDIO_CALLBACK_RESULT_STOP", __func__);