Add the ability to cancel prerender reqeusts and tests

components/offline_pages/background/request_coordinator.cc

Index: components/offline_pages/background/request_coordinator.cc
diff --git a/components/offline_pages/background/request_coordinator.cc b/components/offline_pages/background/request_coordinator.cc
index 41bde51e8ad7870b2e847f95b04429bec738a17c..ae50f7e0855d6722ed216d7bca5198b930fe20d9 100644
--- a/components/offline_pages/background/request_coordinator.cc
+++ b/components/offline_pages/background/request_coordinator.cc
@@ -31,6 +31,8 @@ RequestCoordinator::RequestCoordinator(std::unique_ptr<OfflinerPolicy> policy,
                                        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)),
@@ -95,10 +97,18 @@ bool RequestCoordinator::StartProcessing(
     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;
@@ -115,6 +125,9 @@ void RequestCoordinator::TryNextRequest() {
 }
 
 void RequestCoordinator::StopProcessing() {
+  is_canceled_ = true;
+  if (offliner_ && is_busy_)
+    offliner_->Cancel();
 }
 
 Scheduler::TriggerConditions const&
@@ -123,9 +136,11 @@ RequestCoordinator::GetTriggerConditionsForUserRequest() {
 }
 
 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;
@@ -135,16 +150,16 @@ void RequestCoordinator::SendRequestToOffliner(const SavePageRequest& request) {
   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;
@@ -163,4 +178,10 @@ void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
   }
 }
 
+void RequestCoordinator::GetOffliner() {
+    if (!offliner_) {
+      offliner_ = factory_->GetOffliner(policy_.get());
+    }
+}
+
 }  // namespace offline_pages