Print Jobs: add tooltip for truncated text of print job entries

Screenshot: http://shortn/_9HmkoESwea

Bug: 1122235
Test: manual inspection
Change-Id: I2c02dedb2b6f2201ae147349f60f872b247055bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2386488
Commit-Queue: Michael Checo <michaelcheco@google.com>
Reviewed-by: Jimmy Gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805909}

chromeos/components/print_management/resources/print_job_entry.js

@@ -229,11 +229,34 @@ Polymer({
      */
     showFullOngoingStatus_: Boolean,
   },
+  observers: [
+    'printJobEntryDataChanged_(jobTitle_, printerName_, creationTime_, ' +
+        'completionStatus_)'
+  ],
 
   listeners: {
     'click': 'onClick_',
   },
 
+  /**
+   * Check if any elements with the class "overflow-ellipsis" needs to
+   * add/remove the title attribute.
+   * @private
+   */
+  printJobEntryDataChanged_() {
+    Array.from(this.shadowRoot.querySelectorAll('.overflow-ellipsis')).forEach(
+      (/** @type {HTMLElement} */ e) => {
+        // Checks if text is truncated
+        if (e.offsetWidth < e.scrollWidth) {
+          e.setAttribute("title", e.textContent);
+        }
+        else {
+          e.removeAttribute("title");
+        }
+      }
+                                                                              )
+ },
+
   /** @private */
   onClick_() {
     // Since the status or cancel button has the focus-row-control attribute,