RandomAccessFileReader should not inherit RandomAccessFile

Summary: RandomAccessFileReader unnecessarily inherited RandomAccessFile, which can introduce unnecessarily extra costs. Remove it.

Test Plan: Run all existing tests

Reviewers: yhchiang, anthony, igor, kradhakrishnan, rven, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D47409

table/block_based_table_reader.cc

@@ -617,13 +617,13 @@ void BlockBasedTable::SetupForCompaction() {
     case Options::NONE:
       break;
     case Options::NORMAL:
-      rep_->file->Hint(RandomAccessFile::NORMAL);
+      rep_->file->file()->Hint(RandomAccessFile::NORMAL);
       break;
     case Options::SEQUENTIAL:
-      rep_->file->Hint(RandomAccessFile::SEQUENTIAL);
+      rep_->file->file()->Hint(RandomAccessFile::SEQUENTIAL);
       break;
     case Options::WILLNEED:
-      rep_->file->Hint(RandomAccessFile::WILLNEED);
+      rep_->file->file()->Hint(RandomAccessFile::WILLNEED);
       break;
     default:
       assert(false);

util/file_reader_writer.h

@@ -46,7 +46,7 @@ class SequentialFileReader {
   SequentialFile* file() { return file_.get(); }
 };
 
-class RandomAccessFileReader : public RandomAccessFile {
+class RandomAccessFileReader {
  private:
   std::unique_ptr<RandomAccessFile> file_;
   Env*            env_;