websql: Enable SQLite's defensive mode for WebSQL databases.

The SQLITE_DBCONFIG_DEFENSIVE flag [1] was added in SQLite 3.26 for
applications that run untrusted SQL queries.

[1] https://www.sqlite.org/c3ref/c_dbconfig_defensive.html

Bug: 900910, 910906
Change-Id: Ia749be52b4e03c18df3b25bcb963c7a916fc671a
Reviewed-on: https://chromium-review.googlesource.com/c/1407544
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Joshua Bell <jsbell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622754}
void SQLiteDatabase::UpdateLastChangesCount() {
  if (!db_)
    return;

  last_changes_count_ = sqlite3_total_changes(db_);
}

void SQLiteDatabase::UpdateLastChangesCount() {
  if (!db_)
    return;

  last_changes_count_ = sqlite3_total_changes(db_);
}
