Make error panel items set default text

When a panel item is set to an error type, the primary text can wrap to
2 lines and the secondary text should not be shown.

Change the error panel initialization to set the primary text to a
default generic error string, and the secondary text to blank.

Adds unit test to confirm the expected behaviour.

Bug: 1021307
Tests: browser_tests --gtest_filter=FileManagerJsTest.FilesDisplayPanel
Change-Id: Id9251b9cfae3050dc6fd8005c214d920f6173a44
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1904562
Commit-Queue: Alex Danilo <adanilo@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713729}

ui/file_manager/file_manager/foreground/elements/files_xf_elements_unittest.js

@@ -134,6 +134,33 @@ async function testDisplayPanelChangingPanelTypes(done) {
   done();
 }
 
+function testFilesDisplayPanelErrorText() {
+  // Get the host display panel container element.
+  /** @type {!DisplayPanel|!Element} */
+  const displayPanel = assert(document.querySelector('#test-xf-display-panel'));
+
+  // Add a panel item to the display panel container.
+  const panelItem = displayPanel.addPanelItem('testpanel');
+
+  // Change the primary and secondary text on the panel item.
+  panelItem.primaryText = 'foo';
+  panelItem.secondaryText = 'bar';
+
+  // Check the primary and secondary text has been set on the panel.
+  assertEquals('foo', panelItem.primaryText);
+  assertEquals('bar', panelItem.secondaryText);
+
+  // Change the panel item type to an error panel.
+  panelItem.panelType = panelItem.panelTypeError;
+
+  // Check the default primary text displays a generic error message.
+  // Note, the i18n message gets smooshed into 'An error occurred.' in the app.
+  assertEquals('$i18n{FILE_ERROR_GENERIC}', panelItem.primaryText);
+
+  // Check the secondary text is empty.
+  assertEquals('', panelItem.secondaryText);
+}
+
 // Override the formatting function for unit testing.
 util.strf = (end, option) => {
   return option + end;

ui/file_manager/file_manager/foreground/elements/xf_panel_item.js

@@ -241,6 +241,8 @@ class PanelItem extends HTMLElement {
       case this.panelTypeError:
         this.setAttribute('indicator', 'status');
         this.setAttribute('status', 'failure');
+        this.primaryText = '$i18n{FILE_ERROR_GENERIC}';
+        this.secondaryText = '';
         secondaryButton = document.createElement('xf-button');
         secondaryButton.id = 'secondary-action';
         secondaryButton.onclick = assert(this.onclick);
@@ -515,6 +517,14 @@ class PanelItem extends HTMLElement {
     this.setAttribute('primary-text', text);
   }
 
+  /**
+   * Getter for the primary text on the panel.
+   * @return {string}
+   */
+  get primaryText() {
+    return this.getAttribute('primary-text');
+  }
+
   /**
    * Setter to set the secondary text on the panel.
    * @param {string} text Text to be shown.
@@ -523,6 +533,14 @@ class PanelItem extends HTMLElement {
     this.setAttribute('secondary-text', text);
   }
 
+  /**
+   * Getter for the secondary text on the panel.
+   * @return {string}
+   */
+  get secondaryText() {
+    return this.getAttribute('secondary-text');
+  }
+
   /**
    * Setter to set the panel type.
    * @param {number} type Enum value for the panel type.