Just Following the below simple steps :-
Step 1 : - Open Google Chrome And Head Over To Bookmarks from the right top options menu.
Step 2 :- Then Click On Bookmark Manger option .
Step 3 :- After Clicking, a new tab will open . In that new that click on organize>Export Bookmarks To HTML File...
Step 4 :- Save that HTML File
Done ! You Have Successfully taken backup of your bookmarks