cpplint

Change-Id: I8e69e6403b6d16e9dcfae20b313ebdc685bd47f7

Author: wesm

cpp/src/arrow/io/memory.h

@@ -99,7 +99,7 @@ class ARROW_EXPORT MemoryMappedFile : public ReadWriteFileInterface {
 
 class ARROW_EXPORT BufferReader : public ReadableFileInterface {
  public:
-  BufferReader(const std::shared_ptr<Buffer>& buffer);
+  explicit BufferReader(const std::shared_ptr<Buffer>& buffer);
   BufferReader(const uint8_t* data, int64_t size);
   ~BufferReader();