message: Fix a compile error in file_block_cache_test.cc
diff: @@ -456,7 +456,7 @@ TEST(FileBlockCacheTest, CoalesceConcurrentReads) {
  FileBlockCache cache(block_size, block_size, 0, fetcher);
  // Fork off thread for parallel read.
  std::unique_ptr<Thread> concurrent(
  - Env::Default()->StartThread({}, "concurrent", [&cache] {
  + Env::Default()->StartThread({}, "concurrent", [&cache, block_size] {
  std::vector<char> out;
  TF_EXPECT_OK(cache.Read("", 0, block_size / 2, &out));
  EXPECT_EQ(out.size(), block_size / 2);
  