Made IndexedDB's comparators public.

content/browser/indexed_db/indexed_db_backing_store.h

Index: content/browser/indexed_db/indexed_db_backing_store.h
diff --git a/content/browser/indexed_db/indexed_db_backing_store.h b/content/browser/indexed_db/indexed_db_backing_store.h
index 8e5f7ac0de74b28a9c8233e6f638297da3c46907..e7aa21e16c01f1e522071aeb12ef9b047950f9a1 100644
--- a/content/browser/indexed_db/indexed_db_backing_store.h
+++ b/content/browser/indexed_db/indexed_db_backing_store.h
@@ -12,6 +12,7 @@
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/strings/string_piece.h"
 #include "base/timer/timer.h"
 #include "content/browser/indexed_db/indexed_db.h"
 #include "content/browser/indexed_db/indexed_db_metadata.h"
@@ -45,6 +46,13 @@ class CONTENT_EXPORT IndexedDBBackingStore
  public:
   class CONTENT_EXPORT Transaction;
 
+  class Comparator : public LevelDBComparator {
+   public:
+    virtual int Compare(const base::StringPiece& a,
+                        const base::StringPiece& b) const OVERRIDE;
+    virtual const char* Name() const OVERRIDE;
+  };
+
   const GURL& origin_url() const { return origin_url_; }
   base::OneShotTimer<IndexedDBBackingStore>* close_timer() {
     return &close_timer_;