Fix initialization of AAC presentation struct

Otherwise the new size checks trip on this.

Bug: 27207275
Change-Id: I1f8f01097e3a88ff041b69279a6121be842f1766

void ACodec::waitUntilAllPossibleNativeWindowBuffersAreReturnedToUs() {
 if (mNativeWindow == NULL) {
 return;
 }

 while (countBuffersOwnedByNativeWindow() > mNumUndequeuedBuffers
 && dequeueBufferFromNativeWindow() != NULL) {
 if (storingMetadataInDecodedBuffers() && mMetadataBuffersToSubmit > 0) {
 --mMetadataBuffersToSubmit;
 }
 }
}

void ACodec::waitUntilAllPossibleNativeWindowBuffersAreReturnedToUs() {
 if (mNativeWindow == NULL) {
 return;
 }

 while (countBuffersOwnedByNativeWindow() > mNumUndequeuedBuffers
 && dequeueBufferFromNativeWindow() != NULL) {
 if (storingMetadataInDecodedBuffers() && mMetadataBuffersToSubmit > 0) {
 --mMetadataBuffersToSubmit;
 }
 }
}
