Don't update PageState for a SiteInstance mismatch.

BUG=766262
TEST=See bug for repro.
TBR=lukasza@chromium.org

(cherry picked from commit c050720e317e5223bcbdcaafb816befa789ceaa9)

Change-Id: Ifb087b687acd40d8963ef436c9ea82ca2d960117
Reviewed-on: https://chromium-review.googlesource.com/674808
Commit-Queue: Charlie Reis (OOO until 9/25) <creis@chromium.org>
Reviewed-by: Ɓukasz Anforowicz <lukasza@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#503297}
Reviewed-on: https://chromium-review.googlesource.com/682414
Reviewed-by: Charlie Reis (catching up) <creis@chromium.org>
Cr-Commit-Position: refs/branch-heads/3202@{#439}
Cr-Branched-From: fa6a5d87adff761bc16afc5498c3f5944c1daa68-refs/heads/master@{#499098}
2 files changed