Reland #1 "Reactivate deflaked keyboard accessory tests"

This is a reland of dc92f9db

With this reland, only one of the tests is reenabled again.
The one that doesn't fail and is unrelated to the other two.
(Therefore, the font changes are not needed anymore - this
will follow in a second reland CL).

Original change's description:
> Reactivate deflaked keyboard accessory tests
>
> After having landed https://crrev.com/c/1028230, the problems of the
> linked bug seem to have gone (as assumed).
>
> I removed the Disabling and RetryOnFailure annotations to test on 3
> devices (one physical, two emulator with different screen sizes and OS)
> and couldn't find a single broken test.
> Edit: I changed the font size recently (not finally) which seems to
> bother some bots - unrelated from the filed bug. Changed that back.
>
> This CL now reenables all the tests but keeps the RetryOnFailure
> annotation. That way, I can test whether the tests start failing on
> some bots again without making the sheriffs life harder.
> If the bots don't notice any flakiness, I will remove the
> RetryOnFailure annotation as well and mark the linked bug fixed.
>
> Bug: 838922
> Change-Id: I9781e6d820ac39e43435ad1529da817601967ed4
> Reviewed-on: https://chromium-review.googlesource.com/1044371
> Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
> Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#556798}

Bug: 838922
Change-Id: I18dda9ed9df416a796fa1748032f37adb0224dd0
Reviewed-on: https://chromium-review.googlesource.com/1051831Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557208}

chrome/android/javatests/src/org/chromium/chrome/browser/autofill/AutofillKeyboardAccessoryIntegrationTest.java

@@ -127,7 +127,6 @@ public class AutofillKeyboardAccessoryIntegrationTest {
     @Test
     @MediumTest
     @Feature({"keyboard-accessory"})
-    @DisabledTest(message = "crbug.com/838922")
     public void testTapInputFieldShowsKeyboardAccessory()
             throws ExecutionException, InterruptedException, TimeoutException {
         loadTestPage(false);