CCodecBuffers: fix null buffer PCM conversion

EOS w/ null buffer may be queued, and it needs to go through the
conversion processing to keep the converted format.

Bug: 228576052
Test: atest ccodec_unit_test
Change-Id: I8503132a779aae6bc652ea030d29fc466c8a31a9
diff --git a/media/codec2/sfplugin/CCodecBuffers.cpp b/media/codec2/sfplugin/CCodecBuffers.cpp
index 57c70c1..0f4a8d8 100644
--- a/media/codec2/sfplugin/CCodecBuffers.cpp
+++ b/media/codec2/sfplugin/CCodecBuffers.cpp
@@ -208,7 +208,7 @@
 
 bool OutputBuffers::convert(
         const std::shared_ptr<C2Buffer> &src, sp<Codec2Buffer> *dst) {
-    if (!src || src->data().type() != C2BufferData::LINEAR) {
+    if (src && src->data().type() != C2BufferData::LINEAR) {
         return false;
     }
     int32_t configEncoding = kAudioEncodingPcm16bit;
@@ -237,7 +237,12 @@
     if (!mDataConverter) {
         return false;
     }
-    sp<MediaCodecBuffer> srcBuffer = ConstLinearBlockBuffer::Allocate(mFormat, src);
+    sp<MediaCodecBuffer> srcBuffer;
+    if (src) {
+        srcBuffer = ConstLinearBlockBuffer::Allocate(mFormat, src);
+    } else {
+        srcBuffer = new MediaCodecBuffer(mFormat, new ABuffer(0));
+    }
     if (!srcBuffer) {
         return false;
     }
@@ -1259,8 +1264,8 @@
         if (newBuffer == nullptr) {
             return NO_MEMORY;
         }
+        newBuffer->setFormat(mFormat);
     }
-    newBuffer->setFormat(mFormat);
     *index = mImpl.assignSlot(newBuffer);
     handleImageData(newBuffer);
     *clientBuffer = newBuffer;