Remove old requests from queue, start new requests if any, add test.

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 a6001a04b6e0d9991bbf1a17ff0dcef48122aa8e..033488d57227c93472da575e008ca0f0a4d121af 100644
--- a/components/offline_pages/background/request_coordinator.h
+++ b/components/offline_pages/background/request_coordinator.h
@@ -47,7 +47,7 @@ class RequestCoordinator : public KeyedService {
   // 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 base::Callback<void(bool)>& callback);
+  bool StartProcessing(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
@@ -55,6 +55,16 @@ class RequestCoordinator : public KeyedService {
   // is stopped or complete.
   void StopProcessing();
 
+  // Called by the offliner when an offlining request is completed. (and by
+  // tests).
+  void OfflinerDoneCallback(const SavePageRequest& request,

[dewittj, 2016/06/14 16:16:36]

nit: make this private and make the test harness a friend class.

[Pete Williamson, 2016/06/14 21:03:14]

Done.

+                            Offliner::RequestStatus status);
+
+  // A way for tests to set the callback in use when an operation is over.
+  void SetProcessingCallbackForTest(const base::Callback<void(bool)> callback) {
+    scheduler_callback_ = callback;
+  }
+
   // Returns the request queue used for requests.  Coordinator keeps ownership.
   RequestQueue* queue() { return queue_.get(); }
 
@@ -70,6 +80,8 @@ class RequestCoordinator : public KeyedService {
   void AddRequestResultCallback(RequestQueue::AddRequestResult result,
                                 const SavePageRequest& request);
 
+  void UpdateRequestCallback(RequestQueue::UpdateRequestResult result);
+
   // Callback from the request picker when it has chosen our next request.
   void RequestPicked(const SavePageRequest& request);
 
@@ -78,8 +90,7 @@ class RequestCoordinator : public KeyedService {
 
   void SendRequestToOffliner(const SavePageRequest& request);
 
-  void OfflinerDoneCallback(const SavePageRequest& request,
-                            Offliner::RequestStatus status);
+  void TryNextRequest();
 
   // RequestCoordinator takes over ownership of the policy
   std::unique_ptr<OfflinerPolicy> policy_;
@@ -93,6 +104,8 @@ class RequestCoordinator : public KeyedService {
   Offliner::RequestStatus last_offlining_status_;
   // Class to choose which request to schedule next
   std::unique_ptr<RequestPicker> picker_;
+  // Calling this returns to the scheduler across the JNI bridge.
+  base::Callback<void(bool)> scheduler_callback_;
   // Allows us to pass a weak pointer to callbacks.
   base::WeakPtrFactory<RequestCoordinator> weak_ptr_factory_;