tests: Fix flaky ViewsTextfieldTest.TextfieldKeyEvent

[magreenblatt]

Original report by me.

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What steps will reproduce the problem?

Run ceftests.exe --gtest_filter=Views*.

What is the expected output? What do you see instead?

All tests should pass. Instead, ViewsTextfieldTest.TextfieldKeyEvent reliably fails with:

[ RUN      ] ViewsTextfieldTest.TextfieldKeyEvent
[1004/155404.075:ERROR:textfield.cc(1795)] NOT IMPLEMENTED
../../cef/tests/ceftests/views/textfield_unittest.cc(229): error: Expected equality of these values:
  kTestInputMessage
    Which is: "Test Message"
  textfield->GetText().ToString().c_str()
    Which is: "test Message"
Stack trace:
Backtrace:
        base::debug::StackTrace::StackTrace [0x518D1FB2+34] (C:\code\chromium_git\chromium\src\base\debug\stack_trace.cc:203)

[  FAILED  ] ViewsTextfieldTest.TextfieldKeyEvent (180 ms)

The failure suggests that the EVENTFLAG_SHIFT_DOWN applied in TranslateKey (textfield_unittest.cc) for the first character is somehow getting ignored.

The test usually passes when run by itself or as part of ViewsText*.

The NOT IMPLEMENTED appears harmless.

What version of the product are you using? On what operating system?

M78 and master on Windows 10. It does not appear to be a new failure.

[magreenblatt]

Marked as flaky because running --gtest_filter=ViewsTextfieldTest.TextfieldKeyEvent directly succeeds (at M131).

[magreenblatt]

Also failing consistently on MacOS (M132) with:

../../cef/tests/ceftests/views/textfield_unittest.cc:235: Failure
Expected equality of these values:
  modifiers
    Which is: 2
  event.modifiers
    Which is: 0

[magreenblatt]

Also failing on Linux (M132) with a timeout.