diff --git a/include/media/MediaExtractorPluginHelper.h b/include/media/MediaExtractorPluginHelper.h
index c817b30764..a659660865 100644
--- a/include/media/MediaExtractorPluginHelper.h
+++ b/include/media/MediaExtractorPluginHelper.h
@@ -129,11 +129,13 @@ public:
         mSource = source->mSource;
     }
 
-    ssize_t readAt(off64_t offset, void *data, size_t size) {
+    virtual ~DataSourceHelper() {}
+
+    virtual ssize_t readAt(off64_t offset, void *data, size_t size) {
         return mSource->readAt(mSource->handle, offset, data, size);
     }
 
-    status_t getSize(off64_t *size) {
+    virtual status_t getSize(off64_t *size) {
         return mSource->getSize(mSource->handle, size);
     }
 
@@ -141,7 +143,7 @@ public:
         return mSource->getUri(mSource->handle, uriString, bufferSize);
     }
 
-    uint32_t flags() {
+    virtual uint32_t flags() {
         return mSource->flags(mSource->handle);
     }
 
diff --git a/media/extractors/mp4/MPEG4Extractor.cpp b/media/extractors/mp4/MPEG4Extractor.cpp
index f52d451356..9d2f5d28c5 100644
--- a/media/extractors/mp4/MPEG4Extractor.cpp
+++ b/media/extractors/mp4/MPEG4Extractor.cpp
@@ -198,13 +198,14 @@ private:
 // possibly wrapping multiple times to cover all tracks, i.e.
 // Each CachedRangedDataSource caches the sampletable metadata for a single track.
 
-struct CachedRangedDataSource : public DataSourceHelper {
+class CachedRangedDataSource : public DataSourceHelper {
+public:
     explicit CachedRangedDataSource(DataSourceHelper *source);
     virtual ~CachedRangedDataSource();
 
-    virtual ssize_t readAt(off64_t offset, void *data, size_t size);
-    virtual status_t getSize(off64_t *size);
-    virtual uint32_t flags();
+    ssize_t readAt(off64_t offset, void *data, size_t size) override;
+    status_t getSize(off64_t *size) override;
+    uint32_t flags() override;
 
     status_t setCachedRange(off64_t offset, size_t size, bool assumeSourceOwnershipOnSuccess);
 
@@ -236,7 +237,7 @@ CachedRangedDataSource::CachedRangedDataSource(DataSourceHelper *source)
 CachedRangedDataSource::~CachedRangedDataSource() {
     clearCache();
     if (mOwnsDataSource) {
-        delete (CachedRangedDataSource*)mSource;
+        delete mSource;
     }
 }
 
@@ -366,7 +367,6 @@ MPEG4Extractor::MPEG4Extractor(DataSourceHelper *source, const char *mime)
       mMoofFound(false),
       mMdatFound(false),
       mDataSource(source),
-      mCachedSource(NULL),
       mInitCheck(NO_INIT),
       mHeaderTimescale(0),
       mIsQT(false),
@@ -393,9 +393,6 @@ MPEG4Extractor::~MPEG4Extractor() {
     }
     mPssh.clear();
 
-    if (mCachedSource != mDataSource) {
-        delete mCachedSource;
-    }
     delete mDataSource;
 }
 
@@ -909,8 +906,8 @@ status_t MPEG4Extractor::parseChunk(off64_t *offset, int depth) {
 
                     if (cachedSource->setCachedRange(
                             *offset, chunk_size,
-                            mCachedSource != NULL /* assume ownership on success */) == OK) {
-                        mDataSource = mCachedSource = cachedSource;
+                            true /* assume ownership on success */) == OK) {
+                        mDataSource = cachedSource;
                     } else {
                         delete cachedSource;
                     }
diff --git a/media/extractors/mp4/MPEG4Extractor.h b/media/extractors/mp4/MPEG4Extractor.h
index ca273e082c..b1e04c7c73 100644
--- a/media/extractors/mp4/MPEG4Extractor.h
+++ b/media/extractors/mp4/MPEG4Extractor.h
@@ -33,7 +33,6 @@ namespace android {
 struct AMessage;
 struct CDataSource;
 class DataSourceHelper;
-struct CachedRangedDataSource;
 class SampleTable;
 class String8;
 namespace heif {
@@ -99,7 +98,6 @@ private:
     Vector<Trex> mTrex;
 
     DataSourceHelper *mDataSource;
-    CachedRangedDataSource *mCachedSource;
     status_t mInitCheck;
     uint32_t mHeaderTimescale;
     bool mIsQT;