Reduce SavePasswordPreferencesTest Exceptions test flakiness

By explicitly closing the keyboard before closing the search, the
keyboard will no longer overlay the visible elements in tests.
The slowly disappearing keyboard hid elements from espresso and failed
some test runs on small screen devices.

Change-Id: I45e6548395a3875e79d9cad6a7655e6d67163d2a
Reviewed-on: https://chromium-review.googlesource.com/966034
Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544004}

chrome/android/javatests/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferencesTest.java

@@ -1693,6 +1693,7 @@ public class SavePasswordsPreferencesTest {
                 .check(matches(isDisplayed()));
 
         Espresso.onView(withSearchMenuIdOrText()).perform(click());
+        Espresso.onView(withId(R.id.search_src_text)).perform(click(), closeSoftKeyboard());
 
         Espresso.onView(withText(R.string.section_saved_passwords_exceptions))
                 .check(doesNotExist());