[Android] Remove unused enhanced bookmark code.

We no longer use uncategorized mode.

BUG=451222

Review URL: https://codereview.chromium.org/975383003

Cr-Commit-Position: refs/heads/master@{#319816}

chrome/android/java/src/org/chromium/chrome/browser/enhanced_bookmarks/EnhancedBookmarksModel.java

@@ -19,7 +19,6 @@ import org.chromium.components.bookmarks.BookmarkType;
 import org.chromium.components.dom_distiller.core.DomDistillerUrlUtils;
 import org.chromium.content_public.browser.WebContents;
 
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -164,13 +163,6 @@ public class EnhancedBookmarksModel {
         return mBookmarksBridge.getTopLevelFolderIDs(getSpecial, getNormal);
     }
 
-    /**
-     * @see BookmarksBridge#getUncategorizedBookmarkIDs()
-     */
-    public List<BookmarkId> getUncategorizedBookmarkIDs() {
-        return Collections.emptyList();
-    }
-
     /**
      * @see BookmarksBridge#getAllFoldersWithDepths(List, List)
      */