android: wait for tab counts in TabSwitcherControllerTest.

Should mitigate races between the tests & tabs closing, which
emulators seem to lose much more frequently than devices.

Bug: 1054849
Change-Id: Ifc2bb578ee9a9315b09b32c02b7eba7037fc4941
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2073148Reviewed-by: Sky Malice <skym@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744664}

chrome/test/android/javatests/src/org/chromium/chrome/test/pagecontroller/tests/TabSwitcherControllerTest.java

@@ -20,6 +20,8 @@ import org.chromium.chrome.test.pagecontroller.controllers.tabswitcher.TabSwitch
 import org.chromium.chrome.test.pagecontroller.controllers.tabswitcher.TabSwitcherMenuController;
 import org.chromium.chrome.test.pagecontroller.rules.ChromeUiApplicationTestRule;
 import org.chromium.chrome.test.pagecontroller.rules.ChromeUiAutomatorTestRule;
+import org.chromium.content_public.browser.test.util.Criteria;
+import org.chromium.content_public.browser.test.util.CriteriaHelper;
 
 /**
  * Tests for the TabSwitcherController.
@@ -47,18 +49,27 @@ public class TabSwitcherControllerTest {
         Assert.assertTrue(NewTabPageController.getInstance().isCurrentPageThis());
     }
 
+    private void waitForTabCount(final int count) {
+        CriteriaHelper.pollInstrumentationThread(new Criteria() {
+            @Override
+            public boolean isSatisfied() {
+                return mController.getNumberOfOpenTabs() == count;
+            }
+        });
+    }
+
     @Test
     public void testCloseAllTabs() {
         mController.clickNewTab().openTabSwitcher().clickNewTab().openTabSwitcher();
         mController.clickCloseAllTabs();
-        Assert.assertEquals(0, mController.getNumberOfOpenTabs());
+        waitForTabCount(0);
     }
 
     @Test
     public void testNumberOfOpenTabs() {
         int startTabs = mController.getNumberOfOpenTabs();
         mController.clickNewTab().openTabSwitcher();
-        Assert.assertEquals(startTabs + 1, mController.getNumberOfOpenTabs());
+        waitForTabCount(startTabs + 1);
     }
 
     @Test