[Offline pages] Adding capability to query a subset of requests based on IDs

components/offline_pages/background/request_queue_store.h

Index: components/offline_pages/background/request_queue_store.h
diff --git a/components/offline_pages/background/request_queue_store.h b/components/offline_pages/background/request_queue_store.h
index b661ea0faae1341c06c30b99d709ba70acb44138..bb2e5966e2330f57404b93dcb00ea9205e14f958 100644
--- a/components/offline_pages/background/request_queue_store.h
+++ b/components/offline_pages/background/request_queue_store.h
@@ -38,6 +38,11 @@ class RequestQueueStore {
   // Gets all of the requests from the store.
   virtual void GetRequests(const GetRequestsCallback& callback) = 0;
 
+  // Gets requests with specified IDs from the store. UpdateCallback is used
+  // instead of GetRequestsCallback to indicate which requests where not found.
+  virtual void GetRequestsByIds(const std::vector<int64_t>& request_ids,

[Pete Williamson, 2016/10/11 22:16:21]

I'm not sure it makes sense to have something getting more than one request.  If
the user needs more than one, they will likely do filtering anyway, and it would
be more efficient to have a single SQL query than many SQL queries, one for each
item.

[fgorski, 2016/10/12 20:51:29]

This is actually what we already need:
https://cs.chromium.org/chromium/src/components/offline_pages/background/chan...

[Pete Williamson, 2016/10/12 22:23:36]

In that case, should the changerequeststate task be calling the regular get
instead if there are many entries so we only do one SQL query?  Or should we do
a single SQL query for an any item with an id in a set?  It seems non-performant
to do many SQL queries where one would suffice.

[fgorski, 2016/10/12 23:05:30]

Done. added in _sql.h, as that is where we are pothered by this

+                                const UpdateCallback& callback) = 0;
+
   // Asynchronously adds request in store. Fails if request with the same
   // offline ID already exists.
   virtual void AddRequest(const SavePageRequest& offline_page,