Add a "session only" policy to the content settings.

chrome/browser/renderer_host/database_dispatcher_host.cc

Index: chrome/browser/renderer_host/database_dispatcher_host.cc
diff --git a/chrome/browser/renderer_host/database_dispatcher_host.cc b/chrome/browser/renderer_host/database_dispatcher_host.cc
index eb51fb9867af97faf52a5e242ac46a3e79de1c86..8973881248db59c9989b37395fa1a9db2dd87e51 100644
--- a/chrome/browser/renderer_host/database_dispatcher_host.cc
+++ b/chrome/browser/renderer_host/database_dispatcher_host.cc
@@ -421,9 +421,10 @@ void DatabaseDispatcherHost::OnAllowDatabase(const std::string& origin_url,
 void DatabaseDispatcherHost::AllowDatabaseResponse(
     IPC::Message* reply_msg, ContentSetting content_setting) {
   DCHECK((content_setting == CONTENT_SETTING_ALLOW) ||
-         (content_setting == CONTENT_SETTING_BLOCK));
+         (content_setting == CONTENT_SETTING_BLOCK) ||
+         (content_setting == CONTENT_SETTING_SESSION_ONLY));
   ViewHostMsg_AllowDatabase::WriteReplyParams(
-      reply_msg, content_setting == CONTENT_SETTING_ALLOW);
+      reply_msg, content_setting != CONTENT_SETTING_BLOCK);
   Send(reply_msg);
 }