Provide API in RequestCoordinator to remove results by client ID.

components/offline_pages/background/request_coordinator.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 32 matching lines @@
                      std::unique_ptr<RequestQueue> queue,
                      std::unique_ptr<Scheduler> scheduler);
 
   ~RequestCoordinator() override;
 
   // Queues |request| to later load and save when system conditions allow.
   // Returns true if the page could be queued successfully.
   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
+  // request queue, but does not cancel an in-progress pre-render.

[dougarnett, 2016/07/29 19:01:23]

interesting question about how to deal with a pending request. Canceling would
be clear but if we don't, what happens when request completes and does not find
its original request?

[I think I favor this just being a queue operation and graceful handling of
missing request]

[Pete Williamson, 2016/07/29 22:48:52]

Per offline discussion, let's leave this as is, and later add code to cancel the
pending request.  TODO added.

+  void CancelRequests(const std::vector<ClientId>& client_ids);

[dougarnett, 2016/07/29 19:01:24]

RemoveRequests more accurate since removed requests could already be complete?  

[Pete Williamson, 2016/07/29 22:48:52]

Done.

+
   // 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.
   bool StartProcessing(const DeviceConditions& device_conditions,
                        const base::Callback<void(bool)>& callback);
 
   // Stops the current request processing if active. This is a way for
   // caller to abort processing; otherwise, processing will complete on
   // its own. In either case, the callback will be called when processing
   // is stopped or complete.
@@ skipping 99 matching lines @@
   base::TimeDelta offliner_timeout_;
   // Allows us to pass a weak pointer to callbacks.
   base::WeakPtrFactory<RequestCoordinator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestCoordinator);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_COORDINATOR_H_