Crash Fix: SiteDataDeleteHelper memory corruption

CookiesTreeModel::MaybeNotifyBatchesEnded sets some member variables
after calling TreeModelEndBatch on the observers, but our observer
deletes the CookiesTreeModel object, resulting in memory corruption.

Bug: 766752
Change-Id: I970da0ce1afd829f06d7362ba135c5560ddbff88
Reviewed-on: https://chromium-review.googlesource.com/723788Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509510}

chrome/browser/android/preferences/website_preference_bridge.cc

@@ -588,7 +588,7 @@ class SiteDataDeleteHelper :
     RecursivelyFindSiteAndDelete(cookies_tree_model_->GetRoot());
 
     // This will result in this class getting deleted.
-    Release();
+    BrowserThread::ReleaseSoon(BrowserThread::UI, FROM_HERE, this);
   }
 
   void RecursivelyFindSiteAndDelete(CookieTreeNode* node) {