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 d5e87d26a47a8fd93aa7af30aa2dacef1ad23837..9d7ddfe8fa8e7dd2f9b8895f6d390ba2137199a8 100644
--- a/components/offline_pages/background/request_coordinator.cc
+++ b/components/offline_pages/background/request_coordinator.cc
@@ -22,7 +22,8 @@ RequestCoordinator::RequestCoordinator(std::unique_ptr<OfflinerPolicy> policy,
                                        std::unique_ptr<OfflinerFactory> factory,
                                        std::unique_ptr<RequestQueue> queue,
                                        std::unique_ptr<Scheduler> scheduler)
-    : policy_(std::move(policy)),
+    : offliner_(nullptr),
+      policy_(std::move(policy)),
       factory_(std::move(factory)),
       queue_(std::move(queue)),
       scheduler_(std::move(scheduler)),
@@ -88,10 +89,19 @@ void RequestCoordinator::RequestQueueEmpty() {
 bool RequestCoordinator::StartProcessing(
     const DeviceConditions& device_conditions,
     const base::Callback<void(bool)>& callback) {
+  started_ = false;
+  cancelled_ = false;

[Pete Williamson, 2016/06/22 22:53:22]

FYI - there may be some overlap with the is_busy_ flag in another changelist
(2078113002), I will be merging before this changelist gets submitted.

[chili, 2016/06/23 05:42:06]

nit - we seem to have different spellings of cancelled everywhere, though the
concensus appears to be 'canceled'....

It was confusing with ArchiverResult::CANCELED and then
SavePageResult::CANCELLED

[Pete Williamson, 2016/06/23 16:46:13]

When I checked with a dictionary, both were legit, so I changed mine to
'canceled' for consistency with other code.

   scheduler_callback_ = callback;
   // TODO(petewil): Check existing conditions (should be passed down from
   // BackgroundTask)
 
+  GetOffliner();
+  if (!offliner_) {
+    DVLOG(0) << "Unable to create Offliner. "
+             << "Cannot background offline page.";
+    return false;
+  }
+
   TryNextRequest();
 
   // TODO(petewil): Should return true if the caller should expect a
@@ -112,30 +122,36 @@ void RequestCoordinator::TryNextRequest() {
 }
 
 void RequestCoordinator::StopProcessing() {
+  cancelled_ = true;
+  if (offliner_ && started_)
+    offliner_->Cancel();
 }
 
 void RequestCoordinator::SendRequestToOffliner(const SavePageRequest& request) {
-  // TODO(petewil): Ensure only one offliner at a time is used.
-  // TODO(petewil): When we have multiple offliners, we need to pick one.
-  Offliner* offliner = factory_->GetOffliner(policy_.get());
-  if (!offliner) {
+  if (cancelled_)
+    return;
+  started_ = true;
+
+  GetOffliner();
+  if (!offliner_) {
     DVLOG(0) << "Unable to create Offliner. "
              << "Cannot background offline page.";
     return;
   }
 
   // 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;
+  started_ = false;
 
   // If the request succeeded, remove it from the Queue and maybe schedule
   // another one.
@@ -151,4 +167,10 @@ void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
   }
 }
 
+void RequestCoordinator::GetOffliner() {
+    if (!offliner_) {
+      offliner_ = factory_->GetOffliner(policy_.get());
+    }
+}
+
 }  // namespace offline_pages