[Offline Prefetch] Backoff support for PrefetchBackgroundTask

components/offline_pages/core/prefetch/prefetch_dispatcher.h

 // Copyright 2017 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_CORE_PREFETCH_PREFETCH_DISPATCHER_H_
 #define COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_DISPATCHER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 11 matching lines @@
 class PrefetchDispatcher {
  public:
   // A |ScopedBackgroundTask| is created when we are running in a background
   // task.  Destroying this object should notify the system that we are done
   // processing the background task.
   class ScopedBackgroundTask {
    public:
     ScopedBackgroundTask() = default;
     virtual ~ScopedBackgroundTask() = default;
 
-    // Used on destruction to inform the system about whether rescheduling is
-    // required.
-    virtual void SetNeedsReschedule(bool reschedule) = 0;
+    // Used on destruction to inform the system about whether rescheduling with
+    // or without backoff is required.
+    virtual void SetNeedsReschedule(bool reschedule, bool backoff) = 0;
   };
 
   virtual ~PrefetchDispatcher() = default;
 
   // Initializes the dispatcher with its respective service instance. This must
   // be done before any other methods are called.
   virtual void SetService(PrefetchService* service) = 0;
 
   // Called when a client has candidate URLs for the system to prefetch, along
   // with the client's unique namespace. URLs that are currently in the system
@@ skipping 13 matching lines @@
 
   // Called when Android OS has scheduled us for background work.  When
   // destroyed, |task| will call back and inform the OS that we are done work
   // (if required).  |task| also manages rescheduling behavior.
   virtual void BeginBackgroundTask(
       std::unique_ptr<ScopedBackgroundTask> task) = 0;
 
   // Called when a task must stop immediately due to system constraints. After
   // this call completes, the system will reschedule the task based on whether
   // SetNeedsReschedule has been called.
-  virtual void StopBackgroundTask(ScopedBackgroundTask* task) = 0;
+  virtual void StopBackgroundTask() = 0;
+
+  // Used by the test to signal the completion of the background task.
+  virtual void RequestFinishBackgroundTaskForTest() = 0;
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_CORE_PREFETCH_PREFETCH_DISPATCHER_H_