Fix a flaky thread usage in TabListViewHolderTest

Bug: 1024089
Change-Id: Ie8e0a95b6dd2151cbf88f9e42c0791cc6f264c85
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1913713Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Commit-Queue: Yue Zhang <yuezhanggg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714963}

chrome/android/features/tab_ui/javatests/src/org/chromium/chrome/browser/tasks/tab_management/TabListViewHolderTest.java

@@ -157,12 +157,14 @@ public class TabListViewHolderTest extends DummyUiActivityTestCase {
                                 mSelectedTabBackgroundDrawableId)
                         .build();
 
-        mGridMCP = PropertyModelChangeProcessor.create(
-                mGridModel, mTabGridView, TabGridViewBinder::bindClosableTab);
-        mStripMCP = PropertyModelChangeProcessor.create(
-                mStripModel, mTabStripView, TabStripViewBinder::bind);
-        mSelectableMCP = PropertyModelChangeProcessor.create(
-                mSelectableModel, mSelectableTabGridView, TabGridViewBinder::bindSelectableTab);
+        TestThreadUtils.runOnUiThreadBlocking(() -> {
+            mGridMCP = PropertyModelChangeProcessor.create(
+                    mGridModel, mTabGridView, TabGridViewBinder::bindClosableTab);
+            mStripMCP = PropertyModelChangeProcessor.create(
+                    mStripModel, mTabStripView, TabStripViewBinder::bind);
+            mSelectableMCP = PropertyModelChangeProcessor.create(
+                    mSelectableModel, mSelectableTabGridView, TabGridViewBinder::bindSelectableTab);
+        });
     }
 
     private void testGridSelected(ViewGroup holder, PropertyModel model) {