Remove extern from function declarations.

External linkage is the default for function declarations in C++.

This also fixes ClangTidy errors generated by removing the "extern"
keyword as described above.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188730416

3 files changed, 6 insertions, 6 deletions

diff --git a/table/format.h b/table/format.h
index 6c0b80c..144ff55 100644
--- a/table/format.h
+++ b/table/format.h
@@ -91,10 +91,10 @@ struct BlockContents {
 
 // Read the block identified by "handle" from "file".  On failure
 // return non-OK.  On success fill *result and return OK.
-extern Status ReadBlock(RandomAccessFile* file,
-                        const ReadOptions& options,
-                        const BlockHandle& handle,
-                        BlockContents* result);
+Status ReadBlock(RandomAccessFile* file,
+                 const ReadOptions& options,
+                 const BlockHandle& handle,
+                 BlockContents* result);
 
 // Implementation details follow.  Clients should ignore,
 
diff --git a/table/merger.h b/table/merger.h
index 91ddd80..bafdf5a 100644
--- a/table/merger.h
+++ b/table/merger.h
@@ -18,7 +18,7 @@ class Iterator;
 // key is present in K child iterators, it will be yielded K times.
 //
 // REQUIRES: n >= 0
-extern Iterator* NewMergingIterator(
+Iterator* NewMergingIterator(
     const Comparator* comparator, Iterator** children, int n);
 
 }  // namespace leveldb
diff --git a/table/two_level_iterator.h b/table/two_level_iterator.h
index 629ca34..a93ba89 100644
--- a/table/two_level_iterator.h
+++ b/table/two_level_iterator.h
@@ -20,7 +20,7 @@ struct ReadOptions;
 //
 // Uses a supplied function to convert an index_iter value into
 // an iterator over the contents of the corresponding block.
-extern Iterator* NewTwoLevelIterator(
+Iterator* NewTwoLevelIterator(
     Iterator* index_iter,
     Iterator* (*block_function)(
         void* arg,