Don't prematurely delete script resources when registration is deleted

content/browser/service_worker/service_worker_database.h

Index: content/browser/service_worker/service_worker_database.h
diff --git a/content/browser/service_worker/service_worker_database.h b/content/browser/service_worker/service_worker_database.h
index 6475de04a99e759663456c9224fb40f568eca388..6a708fcc2655347988d73eac3b07647b4e2e50fb 100644
--- a/content/browser/service_worker/service_worker_database.h
+++ b/content/browser/service_worker/service_worker_database.h
@@ -139,10 +139,10 @@ class CONTENT_EXPORT ServiceWorkerDatabase {
   // Deletes a registration for |registration_id| and moves resource records
   // associated with it into the purgeable list. Returns OK if it's successfully
   // deleted or not found in the database. Otherwise, returns an error.
-  Status DeleteRegistration(
-      int64 registration_id,
-      const GURL& origin,
-      std::vector<int64>* newly_purgeable_resources);
+  Status DeleteRegistration(int64 registration_id, const GURL& origin);

[michaeln, 2014/06/28 02:29:31]

The database class should not need to change. It doesn't delete resources it
only moves resourceids from one list to another. The newly_purgeable_resources
return value are those that have been moved to the purgeable list as a result of
this deletion. It's important that all the db changes made by this function
happen in a transaction otherwise there are things in the resource table for
versions that don't exist.

In the schema there are 3 resourceid related tables.

Uncommitted - key: "URES:" + <int64 'uncommitted_resource_id'>
Resource - "RES:" + <int64 'version_id'> + '\x00' + <int64 'resource_id'>
Purgeable - "PRES:" + <int64 'purgeable_resource_id'>


While a version is 'installing', the resourceids for scripts its downloading are
added to the uncommitted list (search for StoreUncommittedReponseId). As part of
committing the registration to store in StoreRegistration, the ids are moved
from the uncommitted list to the 'resource' list. As part of the
DeleteRegistration function, the ids are moved from the resource list to the
purgeable list.

Also as part of StoreRegistration, if the we're overrwriting a previous version
with a new version. The old versions resources are moved to the purgeable list
atomically with the rest of the db updates.

Its done that way so if the program crashes at any point, we have enough info to
cleanup upon restart.

Uncommitted --> dont need those, installations that never completed/committed
Resources --> need all of these
Purgeable --> dont need these either

+
+  Status DeleteVersionResources(int64 version_id,

[michaeln, 2014/06/28 02:29:31]

The seperate DeleteVersionResources method should not be needed.

+                                std::vector<int64>* newly_purgeable_resources);
 
   // As new resources are put into the diskcache, they go into an uncommitted
   // list. When a registration is saved that refers to those ids, they're