[Android][Test] Test metric recording for bottom sheet dismiss button

This CL tests the metric recording for the bottom sheet dismiss button
in the web sign-in flow.

Bug: 1139333
Change-Id: Iafb7fe0528bd5149657a9d92ea3a218fbd9d1228
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2484424Reviewed-by: Tanmoy Mollik <triploblastic@chromium.org>
Commit-Queue: Alice Wang <aliceywang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818406}

chrome/android/javatests/src/org/chromium/chrome/browser/signin/AccountPickerBottomSheetTest.java

@@ -223,6 +223,9 @@ public class AccountPickerBottomSheetTest {
     @Test
     @MediumTest
     public void testDismissCollapsedSheetWithDismissButton() {
+        MetricsUtils.HistogramDelta accountConsistencyHistogram =
+                new HistogramDelta("Signin.AccountConsistencyPromoAction",
+                        AccountConsistencyPromoAction.DISMISSED_BUTTON);
         buildAndShowCollapsedBottomSheet();
         onView(withText(PROFILE_DATA1.getAccountName())).check(matches(isDisplayed()));
         BottomSheetController controller = getBottomSheetController();
@@ -232,6 +235,7 @@ public class AccountPickerBottomSheetTest {
         Assert.assertFalse(controller.isSheetOpen());
         verify(mAccountPickerDelegateMock).onDismiss();
         Assert.assertEquals(0, mFakeProfileDataSource.getNumberOfObservers());
+        Assert.assertEquals(1, accountConsistencyHistogram.getDelta());
     }
 
     @Test