Revert "Fix flaky printmanagement browser test"

This reverts commit 75e29f77.

Reason for revert: Did not fix flaky test

Original change's description:
> Fix flaky printmanagement browser test
> 
> - The original cause of the flaky is because the page element was not
>   ready by the time we try to query for elements within it.
> - The fix is to attach a promise to the instatiation of the page and
>   to only continue with the test once the promise is resolved. This
>   ensures that each step of the test is handled synchronously.
> 
> Bug: 1068860
> Test: browser_tests
> Change-Id: I0a30e2971107b44354603adbb0396ddfea3c218d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2142951
> Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
> Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#757687}

TBR=khorimoto@chromium.org,jimmyxgong@chromium.org

Change-Id: Iecd238842fc5954e922e77a4c0c677814754216f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1068860
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2143517Reviewed-by: jimmy gong <jimmyxgong@chromium.org>
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757762}

chrome/test/data/webui/chromeos/print_management/print_management_test.js

@@ -7,7 +7,7 @@ import 'chrome://resources/mojo/mojo/public/js/mojo_bindings_lite.js';
 import 'chrome://print-management/print_management.js';
 
 import {setMetadataProviderForTesting} from 'chrome://print-management/mojo_interface_provider.js';
-import {flushTasks} from 'chrome://test/test_util.m.js';
+import {flush} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 const CompletionStatus = {
   FAILED: 0,
@@ -84,6 +84,7 @@ function verifyPrintJobs(expected, actual) {
  * @return {!Array<!HTMLElement>}
  */
 function getPrintJobEntries(page) {
+  flush();
   const entryList = page.$$('#entryList');
   return Array.from(
       entryList.querySelectorAll('print-job-entry:not([hidden])'));
@@ -197,7 +198,7 @@ suite('PrintManagementTest', () => {
     mojoApi_.setPrintJobs(printJobs);
     page = document.createElement('print-management');
     document.body.appendChild(page);
-    return flushTasks();
+    flush();
   }
 
   test('PrintHistoryListIsSortedReverseChronologically', () => {
@@ -216,13 +217,11 @@ suite('PrintManagementTest', () => {
     // Initialize with a reversed array of |expectedArr|, since we expect the
     // app to sort the list when it first loads. Since reverse() mutates the
     // original array, use a copy array to prevent mutating |expectedArr|.
-    initializePrintManagementApp(expectedArr.slice().reverse())
-        .then(() => {
-          return mojoApi_.whenCalled('getPrintJobs');
-        })
-        .then(() => {
-          verifyPrintJobs(expectedArr, getPrintJobEntries(page));
-        });
+    initializePrintManagementApp(expectedArr.slice().reverse());
+
+    mojoApi_.whenCalled('getPrintJobs').then(() => {
+      verifyPrintJobs(expectedArr, getPrintJobEntries(page));
+    });
   });
 });