scanning: Show toast when cancel fails

When cancel scan request fails, a toast with error message will pop up,
the scan will continue, and the scan progress page will keep showing.

Bug: 1059779
Change-Id: I9ba3a7a29837f55e8b166224949be1d403e3661c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2559496
Commit-Queue: Gavin Williams <gavinwill@chromium.org>
Reviewed-by: Jesse Schettler <jschettler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832156}

chrome/test/data/webui/chromeos/scanning/scanning_app_test.js

@@ -182,6 +182,15 @@ class FakeScanService {
     return flushTasks();
   }
 
+  /**
+   * @param {boolean} success
+   * @return {!Promise}
+   */
+  simulateCancelComplete(success) {
+    this.scanJobObserverRemote_.onCancelComplete(success);
+    return flushTasks();
+  }
+
   // scanService methods:
 
   /** @return {!Promise<{scanners: !ScannerArr}>} */
@@ -541,7 +550,11 @@ export function scanningAppTest() {
         .then(() => {
           // Click the cancel button to cancel the scan.
           cancelButton.click();
-          return fakeScanService_.cancelScan();
+          return fakeScanService_.whenCalled('cancelScan');
+        })
+        .then(() => {
+          // Simulate cancel completing successfully.
+          return fakeScanService_.simulateCancelComplete(true);
         })
         .then(() => {
           // After canceling is complete, the scan button should be visible and
@@ -551,6 +564,64 @@ export function scanningAppTest() {
         });
   });
 
+  test('CancelScanFailed', () => {
+    const expectedScanners = [
+      createScanner(firstScannerId, firstScannerName),
+    ];
+
+    let capabilities = new Map();
+    capabilities.set(firstScannerId, firstCapabilities);
+
+    /** @type {!CrButtonElement} */
+    let scanButton;
+    /** @type {!CrButtonElement} */
+    let cancelButton;
+
+    return initializeScanningApp(expectedScanners, capabilities)
+        .then(() => {
+          scanButton =
+              /** @type {!CrButtonElement} */ (scanningApp.$$('#scanButton'));
+          cancelButton =
+              /** @type {!CrButtonElement} */ (scanningApp.$$('#cancelButton'));
+          return fakeScanService_.whenCalled('getScannerCapabilities');
+        })
+        .then(() => {
+          // Click the Scan button and wait till the scan is started.
+          scanButton.click();
+          return fakeScanService_.whenCalled('startScan');
+        })
+        .then(() => {
+          // Simulate a progress update and verify the progress bar and text are
+          // updated correctly.
+          return fakeScanService_.simulateProgress(1, 17);
+        })
+        .then(() => {
+          // Click the cancel button to cancel the scan.
+          cancelButton.click();
+          assertFalse(scanningApp.$$('#toast').open);
+          return fakeScanService_.whenCalled('cancelScan');
+        })
+        .then(() => {
+          // Simulate cancel failing.
+          return fakeScanService_.simulateCancelComplete(false);
+        })
+        .then(() => {
+          // After canceling fails, the error toast should pop up.
+          assertTrue(scanningApp.$$('#toast').open);
+          assertEquals(
+              scanningApp.i18n('cancelFailedToastText'),
+              scanningApp.$$('#toastText').textContent.trim());
+          // The scan progress page should still be showing with the cancel
+          // button visible.
+          assertTrue(
+              isVisible(scanningApp.$$('#scanPreview').$$('#scanProgress')));
+          assertTrue(isVisible(cancelButton));
+          assertFalse(
+              isVisible(scanningApp.$$('#scanPreview').$$('#helperText')));
+          assertFalse(isVisible(scanButton));
+        });
+  });
+
   test('ScanFailedToStart', () => {
     const expectedScanners = [
       createScanner(firstScannerId, firstScannerName),

chromeos/chromeos_strings.grd

@@ -582,6 +582,9 @@ Try tapping the mic to ask me anything.
       <message name="IDS_SCANNING_APP_GET_HELP_LINK_TEXT" desc="The text used for the link that navigates to the Scan app help webpage. This is shown to the user after a scanning error.">
         Get help
       </message>
+      <message name="IDS_SCANNING_APP_CANCEL_FAILED_TOAST_TEXT" desc="The error message displayed when a user attempts to cancel a scan job but the cancel request fails.">
+        Couldn't cancel scanning
+      </message>
 
       <!-- Diagnostics App -->
       <!-- TODO(michaelcheco): Update with finalized copies of the strings -->

chromeos/chromeos_strings_grd/IDS_SCANNING_APP_CANCEL_FAILED_TOAST_TEXT.png.sha1

+78e37b5f7d89b511799f4f8c706d997a4f1953d6
\ No newline at end of file

chromeos/components/scanning/resources/scanning_app.js

@@ -256,6 +256,20 @@ Polymer({
     this.setAppState_(AppState.READY);
   },
 
+  /**
+   * Overrides chromeos.scanning.mojom.ScanJobObserverInterface.
+   * @param {boolean} success
+   */
+  onCancelComplete(success) {
+    // If the cancel request fails, continue showing the scan progress page.
+    if (!success) {
+      this.showToast_('cancelFailedToastText');
+      return;
+    }
+
+    this.setAppState_(AppState.READY);
+  },
+
   /**
    * @param {string} selectedSource
    * @return {!Array<chromeos.scanning.mojom.PageSize>}
@@ -414,17 +428,9 @@ Polymer({
   /** @private */
   onCancelClick_() {
     assert(this.appState_ === AppState.SCANNING);
-
     this.scanService_.cancelScan();
-    this.setAppState_(AppState.READY);
   },
 
-  /**
-   * Overrides chromeos.scanning.mojom.ScanJobObserverInterface.
-   * @param {boolean} success
-   */
-  onCancelComplete(success) {},
-
   /**
    * Revokes and removes all of the object URLs.
    * @private

chromeos/components/scanning/scanning_ui.cc

@@ -56,6 +56,7 @@ void AddScanningAppStrings(content::WebUIDataSource* html_source) {
       {"appTitle", IDS_SCANNING_APP_TITLE},
       {"blackAndWhiteOptionText", IDS_SCANNING_APP_BLACK_AND_WHITE_OPTION_TEXT},
       {"cancelButtonText", IDS_SCANNING_APP_CANCEL_BUTTON_TEXT},
+      {"cancelFailedToastText", IDS_SCANNING_APP_CANCEL_FAILED_TOAST_TEXT},
       {"colorModeDropdownLabel", IDS_SCANNING_APP_COLOR_MODE_DROPDOWN_LABEL},
       {"colorOptionText", IDS_SCANNING_APP_COLOR_OPTION_TEXT},
       {"defaultSourceOptionText", IDS_SCANNING_APP_DEFAULT_SOURCE_OPTION_TEXT},