Caching sCachedWindowAndroid is incorrect since it is possible for the
one Application context to be wrapped differently.
There is no point in caching ActivityWindowAndroid either due to the way
ResourcesContextWrapperFactory works.
So remove caching altogether and always create a new WindowAndroid
instance.
BUG=597526
Review URL: https://codereview.chromium.org/1831373003
Cr-Commit-Position: refs/heads/master@{#383408}