Improve syncing between dom distiller and the print preview request

components/dom_distiller/core/dom_distiller_service.h

 // Copyright 2013 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_DOM_DISTILLER_CORE_DOM_DISTILLER_SERVICE_H_
 #define COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_SERVICE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 74 matching lines @@
 
   // Request to view an article by url.
   // Use CreateDefaultDistillerPage() to create a default |distiller_page|.
   // The provided |distiller_page| is only used if there is not already a
   // distillation task in progress for the given |url|.
   virtual scoped_ptr<ViewerHandle> ViewUrl(
       ViewRequestDelegate* delegate,
       scoped_ptr<DistillerPage> distiller_page,
       const GURL& url) = 0;
 
+  virtual scoped_ptr<ViewerHandle> AddViewRequestDelegate(

[nyquist, 2016/01/20 16:59:08]

Please add an explanatory comment as to how this is supposed to be used, and the
expected return values.

What happens if there was no request to distill the URL from before? Does that
do anything? If the distillation has already started, will all callbacks arrive?
If distillation has just finished, what will this return, and what types of
callbacks can you assume?

[mvendramini_hp, 2016/01/21 16:54:46]

Noted. I suggest we keep this pending until we solve the first comment (whether
to use GetOrCreateTaskTrackerForUrl or GetTaskTrackerForUrl, for instance) - as
soon as we agree on that one, we'll add documentation to this new operation.

+      ViewRequestDelegate* delegate,
+      const GURL& url) = 0;
+
   // Creates a default DistillerPage.
   virtual scoped_ptr<DistillerPage> CreateDefaultDistillerPage(
       const gfx::Size& render_view_size) = 0;
   virtual scoped_ptr<DistillerPage> CreateDefaultDistillerPageWithHandle(
       scoped_ptr<SourcePageHandle> handle) = 0;
 
   virtual void AddObserver(DomDistillerObserver* observer) = 0;
   virtual void RemoveObserver(DomDistillerObserver* observer) = 0;
 
   // Returns the DistilledPagePrefs owned by the instance of
@@ skipping 25 matching lines @@
   bool HasEntry(const std::string& entry_id) override;
   std::string GetUrlForEntry(const std::string& entry_id) override;
   std::vector<ArticleEntry> GetEntries() const override;
   scoped_ptr<ArticleEntry> RemoveEntry(const std::string& entry_id) override;
   scoped_ptr<ViewerHandle> ViewEntry(ViewRequestDelegate* delegate,
                                      scoped_ptr<DistillerPage> distiller_page,
                                      const std::string& entry_id) override;
   scoped_ptr<ViewerHandle> ViewUrl(ViewRequestDelegate* delegate,
                                    scoped_ptr<DistillerPage> distiller_page,
                                    const GURL& url) override;
+  scoped_ptr<ViewerHandle> AddViewRequestDelegate(ViewRequestDelegate* delegate,
+                                                  const GURL& url) override;
   scoped_ptr<DistillerPage> CreateDefaultDistillerPage(
       const gfx::Size& render_view_size) override;
   scoped_ptr<DistillerPage> CreateDefaultDistillerPageWithHandle(
       scoped_ptr<SourcePageHandle> handle) override;
   void AddObserver(DomDistillerObserver* observer) override;
   void RemoveObserver(DomDistillerObserver* observer) override;
   DistilledPagePrefs* GetDistilledPagePrefs() override;
 
  private:
   void CancelTask(TaskTracker* task);
@@ skipping 24 matching lines @@
 
   typedef ScopedVector<TaskTracker> TaskList;
   TaskList tasks_;
 
   DISALLOW_COPY_AND_ASSIGN(DomDistillerService);
 };
 
 }  // namespace dom_distiller
 
 #endif  // COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_SERVICE_H_