Add virtual destructors to ByteStream* (#20417)

Author: stuartmorgan-g

shell/platform/common/cpp/client_wrapper/byte_buffer_streams.h

@@ -23,6 +23,8 @@ class ByteBufferStreamReader : public ByteStreamReader {
   explicit ByteBufferStreamReader(const uint8_t* bytes, size_t size)
       : bytes_(bytes), size_(size) {}
 
+  virtual ~ByteBufferStreamReader() = default;
+
   // |ByteStreamReader|
   uint8_t ReadByte() override {
     if (location_ >= size_) {
@@ -69,6 +71,8 @@ class ByteBufferStreamWriter : public ByteStreamWriter {
     assert(buffer);
   }
 
+  virtual ~ByteBufferStreamWriter() = default;
+
   // |ByteStreamWriter|
   void WriteByte(uint8_t byte) { bytes_->push_back(byte); }
 

shell/platform/common/cpp/client_wrapper/include/flutter/byte_streams.h

@@ -12,6 +12,9 @@ namespace flutter {
 // An interface for a class that reads from a byte stream.
 class ByteStreamReader {
  public:
+  explicit ByteStreamReader() = default;
+  virtual ~ByteStreamReader() = default;
+
   // Reads and returns the next byte from the stream.
   virtual uint8_t ReadByte() = 0;
 
@@ -48,6 +51,9 @@ class ByteStreamReader {
 // An interface for a class that writes to a byte stream.
 class ByteStreamWriter {
  public:
+  explicit ByteStreamWriter() = default;
+  virtual ~ByteStreamWriter() = default;
+
   // Writes |byte| to the stream.
   virtual void WriteByte(uint8_t byte) = 0;