Speculating that ...PPAPITest.ImeInputEvent tests are not flaky anymore.

An earlier CL (https://crrev.com/c/1970834) realized that IME tests
depend on focus/activation state of the browser window, and to fix
test failures moved OutOfProcessPPAPITest.ImeInputEvent test from
browser_tests to interactive_ui_tests.

In this CL we speculate that the flakiness tracked in
https://crbug.com/135403 was caused by running focus-dependent tests
in browser_tests + that the flakiness is gone now and the tests can
be re-enabled on Linux and Windows.

Fixed: 135403
Change-Id: I2b650b213fea722d82cb8e45b792f7c2d0da576f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1995500
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737834}

chrome/test/ppapi/ppapi_interactive_browsertest.cc

@@ -25,12 +25,6 @@ IN_PROC_BROWSER_TEST_F(OutOfProcessPPAPITest,
   RunTestViaHTTP("MouseLock_SucceedWhenAllowed");
 }
 
-// Flaky on Linux and Windows. http://crbug.com/135403
-#if defined(OS_LINUX) || defined(OS_WIN)
-#define MAYBE_ImeInputEvent DISABLED_ImeInputEvent
-#else
-#define MAYBE_ImeInputEvent ImeInputEvent
-#endif
-IN_PROC_BROWSER_TEST_F(OutOfProcessPPAPITest, MAYBE_ImeInputEvent) {
+IN_PROC_BROWSER_TEST_F(OutOfProcessPPAPITest, ImeInputEvent) {
   RunTest(ppapi::StripTestPrefixes("ImeInputEvent"));
 }