[sql] Consider fresh databases suitable for memory-mapped I/O.

content/browser/dom_storage/dom_storage_database.cc

Index: content/browser/dom_storage/dom_storage_database.cc
diff --git a/content/browser/dom_storage/dom_storage_database.cc b/content/browser/dom_storage/dom_storage_database.cc
index 1e0166f68f849f157e55b25e199f917416a70b92..b19dffa6c2fb947c499cc8cb854b3d388f8a0a06 100644
--- a/content/browser/dom_storage/dom_storage_database.cc
+++ b/content/browser/dom_storage/dom_storage_database.cc
@@ -151,6 +151,10 @@ bool DOMStorageDatabase::LazyOpen(bool create_if_needed) {
   db_.reset(new sql::Connection());
   db_->set_histogram_tag("DOMStorageDatabase");
 
+  // TODO(shess): The current mitigation for http://crbug.com/537742 stores
+  // state in the meta table, which this database does not use.
+  db_->set_mmap_disabled();
+
   if (file_path_.empty()) {
     // This code path should only be triggered by unit tests.
     if (!db_->OpenInMemory()) {