Add the ability to cancel prerender reqeusts and tests

components/offline_pages/background/request_coordinator.cc

 // 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.
 
 #include "components/offline_pages/background/request_coordinator.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 13 matching lines @@
     false /* require_power_connected */,
     50 /* minimum_battery_percentage */,
     false /* require_unmetered_network */);
 }  // namespace
 
 RequestCoordinator::RequestCoordinator(std::unique_ptr<OfflinerPolicy> policy,
                                        std::unique_ptr<OfflinerFactory> factory,
                                        std::unique_ptr<RequestQueue> queue,
                                        std::unique_ptr<Scheduler> scheduler)
     : is_busy_(false),
+      is_canceled_(false),
+      offliner_(nullptr),
       policy_(std::move(policy)),
       factory_(std::move(factory)),
       queue_(std::move(queue)),
       scheduler_(std::move(scheduler)),
       last_offlining_status_(Offliner::RequestStatus::UNKNOWN),
       weak_ptr_factory_(this) {
   DCHECK(policy_ != nullptr);
   picker_.reset(new RequestPicker(queue_.get()));
 }
 
@@ skipping 44 matching lines @@
   scheduler_callback_.Run(true);
 }
 
 // Returns true if the caller should expect a callback, false otherwise. For
 // instance, this would return false if a request is already in progress.
 bool RequestCoordinator::StartProcessing(
     const DeviceConditions& device_conditions,
     const base::Callback<void(bool)>& callback) {
   if (is_busy_) return false;
 
+  is_canceled_ = false;
   scheduler_callback_ = callback;
   // TODO(petewil): Check existing conditions (should be passed down from
   // BackgroundTask)
 
+  GetOffliner();

[dougarnett, 2016/06/23 17:19:17]

I wonder about this check here. Maybe you can say more about why it is here.
Seems like we may want to get appropriate Offline once we have the next request
(at least down the road if the request helps determine which offliner if more
than one).

[Pete Williamson, 2016/06/23 17:54:53]

My thought here was that if we can't get an offliner that we should quit early
instead of after some async steps.  It can easily be removed so we can make the
decision later.

Removed the check.

+  if (!offliner_) {
+    DVLOG(0) << "Unable to create Offliner. "
+             << "Cannot background offline page.";
+    return false;
+  }
+
   TryNextRequest();
 
   return true;
 }
 
 void RequestCoordinator::TryNextRequest() {
   // Choose a request to process that meets the available conditions.
   // This is an async call, and returns right away.
   picker_->ChooseNextRequest(
       base::Bind(&RequestCoordinator::RequestPicked,
                  weak_ptr_factory_.GetWeakPtr()),
       base::Bind(&RequestCoordinator::RequestQueueEmpty,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void RequestCoordinator::StopProcessing() {
+  is_canceled_ = true;
+  if (offliner_ && is_busy_)
+    offliner_->Cancel();
 }
 
 Scheduler::TriggerConditions const&
 RequestCoordinator::GetTriggerConditionsForUserRequest() {
   return kUserRequestTriggerConditions;
 }
 
 void RequestCoordinator::SendRequestToOffliner(const SavePageRequest& request) {
-  // TODO(petewil): When we have multiple offliners, we need to pick one.
-  Offliner* offliner = factory_->GetOffliner(policy_.get());
-  if (!offliner) {
+  if (is_canceled_)

[dougarnett, 2016/06/23 17:19:17]

// Be sure processing hasn't been canceled.

[Pete Williamson, 2016/06/23 17:54:53]

Comment added (I worded it slightly differently).

+    return;
+
+  GetOffliner();
+  if (!offliner_) {
     DVLOG(0) << "Unable to create Offliner. "
              << "Cannot background offline page.";
     return;
   }
 
   DCHECK(!is_busy_);
   is_busy_ = true;
 
   // Start the load and save process in the offliner (Async).
-  offliner->LoadAndSave(request,
-                        base::Bind(&RequestCoordinator::OfflinerDoneCallback,
-                                   weak_ptr_factory_.GetWeakPtr()));
+  offliner_->LoadAndSave(request,
+                         base::Bind(&RequestCoordinator::OfflinerDoneCallback,
+                                    weak_ptr_factory_.GetWeakPtr()));
 }
 
 void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
                                               Offliner::RequestStatus status) {
   DVLOG(2) << "offliner finished, saved: "
-           << (status == Offliner::RequestStatus::SAVED) << ", "
-           << __FUNCTION__;
+           << (status == Offliner::RequestStatus::SAVED) << ", status: "
+           << (int) status << ", " << __FUNCTION__;
   last_offlining_status_ = status;
 
   is_busy_ = false;
 
   // If the request succeeded, remove it from the Queue and maybe schedule
   // another one.
   if (status == Offliner::RequestStatus::SAVED) {
     queue_->RemoveRequest(request.request_id(),
                           base::Bind(&RequestCoordinator::UpdateRequestCallback,
                                      weak_ptr_factory_.GetWeakPtr()));
 
     // TODO(petewil): Check time budget. Return to the scheduler if we are out.
 
     // Start another request if we have time.
     TryNextRequest();
   }
 }
 
+void RequestCoordinator::GetOffliner() {
+    if (!offliner_) {
+      offliner_ = factory_->GetOffliner(policy_.get());
+    }
+}
+
 }  // namespace offline_pages