Provide API in RequestCoordinator to remove results by client ID.

components/offline_pages/background/request_coordinator.h

Index: components/offline_pages/background/request_coordinator.h
diff --git a/components/offline_pages/background/request_coordinator.h b/components/offline_pages/background/request_coordinator.h
index c757702b01bace4e290c725600225bb70b7e3e28..152834214fca260c329cacbecbde39550ade4801 100644
--- a/components/offline_pages/background/request_coordinator.h
+++ b/components/offline_pages/background/request_coordinator.h
@@ -50,6 +50,11 @@ class RequestCoordinator : public KeyedService {
   bool SavePageLater(
       const GURL& url, const ClientId& client_id, bool user_reqeusted);
 
+  // Cancel a list of requests by |client_id|.  This removes requests from the

[dougarnett, 2016/08/01 18:28:35]

Remove ...

[Pete Williamson, 2016/08/01 23:23:07]

Done.

+  // request queue, but does not cancel an in-progress pre-render.
+  // TODO(petewil): Add code to cancel an in-progress pre-render.
+  void RemoveRequests(const std::vector<ClientId>& client_ids);

[Dmitry Titov, 2016/08/01 19:37:29]

Can we add a callback? It's an async operation, and UI bridge has to provide an
observer call to UI when the item is actually removed for consistent update.

[Pete Williamson, 2016/08/01 23:23:07]

As we discussed offline, we are providing an observer we can use instead.

+
   // Starts processing of one or more queued save page later requests.
   // Returns whether processing was started and that caller should expect
   // a callback. If processing was already active, returns false.