Deflake WidgetInputMethodInteractiveTest.TwoTopWindows on Linux
Deflake WidgetInputMethodInteractiveTest.TwoTopWindows on Linux

I was able to repro the flake with ~1% probability and traced.

It was flaky because earlier window server messages were still pending
when the test started running checks. So the first `ActivateSync` would
actually break out of the message loop wait too soon.

BUG=484836

Review URL: https://codereview.chromium.org/1130683004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#329267}

hgl888/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,hgl888/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Chilledheart/chromium,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Fireblend/chromium-crosswalk,Fireblend/chromium-crosswalk,Chilledheart/chromium,Fireblend/chromium-crosswalk,Just-D/chromium-1,hgl888/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,hgl888/chromium-crosswalk,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Pluto-tv/chromium-crosswalk,hgl888/chromium-crosswalk,Just-D/chromium-1,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Just-D/chromium-1,Just-D/chromium-1,Chilledheart/chromium,Just-D/chromium-1,Chilledheart/chromium,Just-D/chromium-1,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,axinging/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,hgl888/chromium-crosswalk,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Just-D/chromium-1,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,Fireblend/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Chilledheart/chromium,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk