Make getMinimumVersionCode thread safe.

The method is not thread safe when there are multiple available-by-default,
non-fallback WebView provider packages with different versions, because it sets
mMiniumVersionCode multiple times during the for loop, when another thread might
be reading the intermediate mMinimumVersionCode.

BUG: 28916406
Change-Id: I826c79f108b114c42c7bcd91fc198212c9ab09ad
1 file changed