[breadcrumb] Make getBreadcrumbButtons private

This API was public: I assumed I would need for testing. Turns out no,
it's not needed for testing, so make it private.

Bug: 1035691, 1061388
Change-Id: I1672d1e9764de5d98ba87b29f0a7823a35dda844
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2143095
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757726}

ui/file_manager/file_manager/foreground/js/ui/breadcrumb.js

@@ -311,8 +311,9 @@ class BreadCrumb extends HTMLElement {
    * its parts, which are stored in the <button>.textContent.
    *
    * @return {!Array<HTMLButtonElement>}
+   * @private
    */
-  getBreadcrumbButtons() {
+  getBreadcrumbButtons_() {
     const parts = this.shadowRoot.querySelectorAll('button[id]:not([hidden])');
     if (this.parts_.length <= 4) {
       return Array.from(parts);
@@ -332,7 +333,7 @@ class BreadCrumb extends HTMLElement {
    *    attribute on the returned buttons.
    */
   getEllipsisButtons() {
-    return this.getBreadcrumbButtons().filter(button => {
+    return this.getBreadcrumbButtons_().filter(button => {
       if (!button.hasAttribute('has-tooltip') && button.offsetWidth) {
         return button.offsetWidth < button.scrollWidth;
       }
@@ -375,7 +376,7 @@ class BreadCrumb extends HTMLElement {
     }
 
     if (element instanceof HTMLButtonElement) {
-      const parts = this.getBreadcrumbButtons();
+      const parts = this.getBreadcrumbButtons_();
       this.signal_(parts.indexOf(element));
     }
   }