Add MediaBufferBase and use it in MediaSource and MediaBufferGroup.

MediaBuffer class exposes internal classes, ABuffer and IMemory, which
we don't want to expose to plugins. This change introduces
MediaBufferBase which does not expose any classes from system library.

Test: build and post-submit media cts tests
Bug: 67908556
Change-Id: Ic9ee239caf9b84b2b3740e2d533257afa25c8784
diff --git a/media/libmediaplayerservice/nuplayer/GenericSource.cpp b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
index 511f46f..b0c82f2 100644
--- a/media/libmediaplayerservice/nuplayer/GenericSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
@@ -1143,7 +1143,7 @@
 }
 
 sp<ABuffer> NuPlayer::GenericSource::mediaBufferToABuffer(
-        MediaBuffer* mb,
+        MediaBufferBase* mb,
         media_track_type trackType) {
     bool audio = trackType == MEDIA_TRACK_TYPE_AUDIO;
     size_t outLength = mb->range_length();
@@ -1326,7 +1326,7 @@
 
     int32_t generation = getDataGeneration(trackType);
     for (size_t numBuffers = 0; numBuffers < maxBuffers; ) {
-        Vector<MediaBuffer *> mediaBuffers;
+        Vector<MediaBufferBase *> mediaBuffers;
         status_t err = NO_ERROR;
 
         sp<IMediaSource> source = track->mSource;
@@ -1335,7 +1335,7 @@
             err = source->readMultiple(
                     &mediaBuffers, maxBuffers - numBuffers, &options);
         } else {
-            MediaBuffer *mbuf = NULL;
+            MediaBufferBase *mbuf = NULL;
             err = source->read(&mbuf, &options);
             if (err == OK && mbuf != NULL) {
                 mediaBuffers.push_back(mbuf);
@@ -1358,7 +1358,7 @@
 
         for (; id < count; ++id) {
             int64_t timeUs;
-            MediaBuffer *mbuf = mediaBuffers[id];
+            MediaBufferBase *mbuf = mediaBuffers[id];
             if (!mbuf->meta_data()->findInt64(kKeyTime, &timeUs)) {
                 mbuf->meta_data()->dumpToLog();
                 track->mPackets->signalEOS(ERROR_MALFORMED);
@@ -1654,7 +1654,7 @@
     return OK;
 }
 
-void NuPlayer::GenericSource::signalBufferReturned(MediaBuffer *buffer)
+void NuPlayer::GenericSource::signalBufferReturned(MediaBufferBase *buffer)
 {
     //ALOGV("signalBufferReturned %p  refCount: %d", buffer, buffer->localRefcount());