Add a DistilledContentStore (and an in-memory impl)

components/dom_distiller/core/task_tracker.h

Index: components/dom_distiller/core/task_tracker.h
diff --git a/components/dom_distiller/core/task_tracker.h b/components/dom_distiller/core/task_tracker.h
index dc066beeb5419ba7718de95eac5c7764b61ccf2a..260ce8a90a3ed40a0210a164c4f890d5c0ced374 100644
--- a/components/dom_distiller/core/task_tracker.h
+++ b/components/dom_distiller/core/task_tracker.h
@@ -21,6 +21,7 @@ class GURL;
 namespace dom_distiller {
 
 class DistilledArticleProto;
+class DistilledContentStore;
 
 // A handle to a request to view a DOM distiller entry or URL. The request will
 // be cancelled when the handle is destroyed.
@@ -75,7 +76,9 @@ class TaskTracker {
       void(const ArticleEntry&, const DistilledArticleProto*, bool)>
       SaveCallback;
 
-  TaskTracker(const ArticleEntry& entry, CancelCallback callback);
+  TaskTracker(const ArticleEntry& entry,
+              CancelCallback callback,
+              DistilledContentStore* content_store);
   ~TaskTracker();
 
   // |factory| will not be stored after this call.
@@ -95,6 +98,8 @@ class TaskTracker {
 
  private:
   void OnDistillerFinished(scoped_ptr<DistilledArticleProto> distilled_article);
+  void OnBlobFetched(bool success,
+                     scoped_ptr<DistilledArticleProto> distilled_article);
 
   void OnDistilledArticleReady(
       scoped_ptr<DistilledArticleProto> distilled_article);
@@ -113,14 +118,16 @@ class TaskTracker {
   void MaybeCancel();
 
   CancelCallback cancel_callback_;
-  std::vector<SaveCallback> save_callbacks_;
 
-  scoped_ptr<Distiller> distiller_;
+  DistilledContentStore* content_store_;
 
+  std::vector<SaveCallback> save_callbacks_;
   // A ViewRequestDelegate will be added to this list when a view request is
   // made and removed when the corresponding ViewerHandle is destroyed.
   std::vector<ViewRequestDelegate*> viewers_;
 
+  scoped_ptr<Distiller> distiller_;
+
   ArticleEntry entry_;
   scoped_ptr<DistilledArticleProto> distilled_article_;