[extensions] Don't let clicks on <a href="#"> links escape un-prevented.

chrome/browser/resources/shared/js/util.js

Index: chrome/browser/resources/shared/js/util.js
diff --git a/chrome/browser/resources/shared/js/util.js b/chrome/browser/resources/shared/js/util.js
index 729d7d5da017e2b485139ad7f008d93a4e6e1fc7..7c1b5c288aa1abd8f98004ff87fac060e7ee2449 100644
--- a/chrome/browser/resources/shared/js/util.js
+++ b/chrome/browser/resources/shared/js/util.js
@@ -129,6 +129,17 @@ function disableTextSelectAndDrag(opt_allowSelectStart, opt_allowDragStart) {
 }
 
 /**
+ * Call this to stop clicks on <a href="#"> links from scrolling to the top of
+ * the page (and possibly showing a # in the link).
+ */
+function preventDefaultOnPoundLinkClicks() {
+  document.addEventListener('click', function(e) {
+    if (e.target.nodeName == 'A' && e.target.getAttribute('href') == '#')
+      e.preventDefault();
+  });
+}
+
+/**
  * Check the directionality of the page.
  * @return {boolean} True if Chrome is running an RTL UI.
  */