Fixing null pointer dereference.

BUG=chromium:158178
TEST=units,make sure such SEGV doesnt happen on x86-generic-bot (where it pops periodically now)


Review URL: https://chromiumcodereview.appspot.com/11886065

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@177399 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/sql/connection.h b/sql/connection.h
index b9f45ec4..2722ffd 100644
--- a/sql/connection.h
+++ b/sql/connection.h
@@ -370,8 +370,9 @@
     // When true, the statement can be used.
     bool is_valid() const { return !!stmt_; }
 
-    // If we've not been linked to a connection, this will be NULL. Guaranteed
-    // non-NULL when is_valid().
+    // If we've not been linked to a connection, this will be NULL.
+    // TODO(shess): connection_ can be NULL in case of GetUntrackedStatement(),
+    // which prevents Statement::OnError() from forwarding errors.
     Connection* connection() const { return connection_; }
 
     // Returns the sqlite statement if any. If the statement is not active,