Add Finch experiment to cookie monster.

content/browser/net/sqlite_persistent_cookie_store.cc

Index: content/browser/net/sqlite_persistent_cookie_store.cc
diff --git a/content/browser/net/sqlite_persistent_cookie_store.cc b/content/browser/net/sqlite_persistent_cookie_store.cc
index eaf793047a9b0b8cf28803ef9d84c69d418d74dd..40a763368897b0bd6bf1e0c4c9c20efaff53c75c 100644
--- a/content/browser/net/sqlite_persistent_cookie_store.cc
+++ b/content/browser/net/sqlite_persistent_cookie_store.cc
@@ -431,8 +431,6 @@ bool InitTable(sql::Connection* db) {
 
 void SQLitePersistentCookieStore::Backend::Load(
     const LoadedCallback& loaded_callback) {
-  // This function should be called only once per instance.
-  DCHECK(!db_.get());
   PostBackgroundTask(FROM_HERE, base::Bind(
       &Backend::LoadAndNotifyInBackground, this,
       loaded_callback, base::Time::Now()));
@@ -469,6 +467,8 @@ void SQLitePersistentCookieStore::Backend::LoadAndNotifyInBackground(
     PostClientTask(FROM_HERE, base::Bind(
         &Backend::CompleteLoadInForeground, this, loaded_callback, false));
   } else {
+    if (!restore_old_session_cookies_)
+      DeleteSessionCookiesOnStartup();

[erikwright (departed), 2015/04/07 22:37:09]

Isn't this ineffective here? I would think it should be called from
FinishedLoadingCookies, or (if you follow my next suggestion to make it take a
key) at the end of ChainLoadCookies?

     ChainLoadCookies(loaded_callback);
   }
 }
@@ -488,6 +488,8 @@ void SQLitePersistentCookieStore::Backend::LoadKeyAndNotifyInBackground(
 
   bool success = false;
   if (InitializeDatabase()) {
+    if (!restore_old_session_cookies_)
+      DeleteSessionCookiesOnStartup();

[erikwright (departed), 2015/04/07 22:37:09]

This makes me think that, in fact, we have a bug as follows:

* Domain X is loaded.
* A session cookie for domain X is received and stored.
* Some other domains are loaded, completing the load.
* All session cookies are deleted.

This would only delete them from disk (not memory) so the only user-visible
problem is after a session restore.

Your change doesn't cause the bug, just changes the mechanism somewhat.

ideally, DeleteSessionClookiesOnStartup should take a domain key and restrict
its operation to that key.

[erikchen, 2015/04/08 17:44:26]

I agree that the previous behavior was incorrect. 

I don't understand why you want to DeleteSessionClookiesOnStartup() by
individual keys. I moved the call into InitializeDatabase(), so it happens
exactly once, immediately after startup, before any cookies are loaded into
memory. That prevents it from deleting session cookies from the current session,
and also ensures that memory/database are in sync.

     std::map<std::string, std::set<std::string> >::iterator
       it = keys_to_load_.find(key);
     if (it != keys_to_load_.end()) {
@@ -1268,8 +1270,6 @@ void SQLitePersistentCookieStore::Backend::FinishedLoadingCookies(
     bool success) {
   PostClientTask(FROM_HERE, base::Bind(&Backend::CompleteLoadInForeground, this,
                                        loaded_callback, success));
-  if (success && !restore_old_session_cookies_)
-    DeleteSessionCookiesOnStartup();
 }
 
 SQLitePersistentCookieStore::SQLitePersistentCookieStore(