Add calls to the offliner and unit tests.

components/offline_pages/background/offliner.h

 // 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.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_BACKGROUND_OFFLINER_H_
 #define COMPONENTS_OFFLINE_PAGES_BACKGROUND_OFFLINER_H_
 
 #include "base/callback.h"
 
 namespace offline_pages {
 
 class SavePageRequest;
 
 // Interface of a class responsible for constructing an offline page given
 // a request with a URL.
 class Offliner {
  public:
   // Completion status of processing an offline page request.
   enum CompletionStatus {
     SAVED = 0,
     CANCELED = 1,
     FAILED_CONSIDER_RETRY = 2,
     FAILED_DO_NOT_RETRY = 3,
+    NO_STATUS_YET = 4,

[dougarnett, 2016/05/13 19:33:00]

How about "UNKNOWN"? My pending CL adds new enum with that name

[Btw, my CL is currently renaming CompletionStatus to RequestStatus as I want to
use the same enum from Loader to Offliner to report new LOADED value.]

[Pete Williamson, 2016/05/13 22:28:24]

Done.

   };
 
   // Reports the completion status of a request.
   // TODO(dougarnett): consider passing back a request id instead of request.
   typedef base::Callback<void(const SavePageRequest&, CompletionStatus)>
       CompletionCallback;
 
   Offliner() {}
   virtual ~Offliner() {}
 
   // Processes |request| to load and save an offline page.
   // Returns whether the request was accepted or not.
   virtual bool LoadAndSave(
       const SavePageRequest& request,
       const CompletionCallback& callback) = 0;
 
   // Clears the currently processing request, if any.
   virtual void Cancel() = 0;
 
   // TODO(dougarnett): add policy support methods.
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_OFFLINER_H_