Remove obsolete keywords table migrating function

components/search_engines/keyword_table.h

Index: components/search_engines/keyword_table.h
diff --git a/components/search_engines/keyword_table.h b/components/search_engines/keyword_table.h
index 16a4474c6385a46770a3113f8cb5260731ea1f13..bbc6a0ede9e48dd0d517ac55cb3f2995a11fb578 100644
--- a/components/search_engines/keyword_table.h
+++ b/components/search_engines/keyword_table.h
@@ -165,10 +165,6 @@ class KeywordTable : public WebDatabaseTable {
                           const std::string& table_name,
                           std::string* result);
 
-  // Migrates table |name| (which should be either "keywords" or
-  // "keywords_backup") from version 44 to version 45.
-  bool MigrateKeywordsTableForVersion45(const std::string& name);
-
   DISALLOW_COPY_AND_ASSIGN(KeywordTable);
 };