[Android Webapp] Remove unneeded SameActivityWebappSplashDelegate#mInitializedLayout 7/9

BUG=918459

Change-Id: I6d374062b3ffe3d8aaed825531fd121b731bbbb6
Reviewed-on: https://chromium-review.googlesource.com/c/1425560
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625485}
1 file changed