Fix uninitialized memory error in BrowserProcessImpl

TBR=sky@chromium.org

Bug: 784792
Change-Id: Ib1cb7e3d38f887ce7e1411c06e40d4d58f677ea7
Reviewed-on: https://chromium-review.googlesource.com/768381Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516257}

chrome/browser/browser_process_impl.cc

@@ -222,6 +222,7 @@ BrowserProcessImpl::BrowserProcessImpl(
       created_notification_bridge_(false),
       created_safe_browsing_service_(false),
       created_subresource_filter_ruleset_service_(false),
+      created_optimization_guide_service_(false),
       shutting_down_(false),
       tearing_down_(false),
       download_status_updater_(base::MakeUnique<DownloadStatusUpdater>()),