Add incremental updates for multipage distillation.

components/dom_distiller/core/article_distillation_update.h

Index: components/dom_distiller/core/article_distillation_update.h
diff --git a/components/dom_distiller/core/article_distillation_update.h b/components/dom_distiller/core/article_distillation_update.h
new file mode 100644
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+++ b/components/dom_distiller/core/article_distillation_update.h
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+// Copyright 2014 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_ARTICLE_DISTILLATION_UPDATE_H_
+#define COMPONENTS_DOM_DISTILLER_CORE_ARTICLE_DISTILLATION_UPDATE_H_
+
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "components/dom_distiller/core/proto/distilled_page.pb.h"
+
+namespace dom_distiller {
+
+// Update about an article that is currently under distillation.
+class ArticleDistillationUpdate {
+ public:
+  typedef base::RefCountedData<DistilledPageProto> RefCountedPageProto;
+
+  ArticleDistillationUpdate(
+      const std::vector<scoped_refptr<RefCountedPageProto> >& pages,
+      bool has_next_page,
+      bool has_prev_page);
+  ~ArticleDistillationUpdate();
+
+  // Returns the  distilled page at |index|.
+  const DistilledPageProto& GetDistilledPage(size_t index) const;
+
+  // Returns the size of distilled pages in this update.
+  size_t GetPagesSize() const { return pages_.size(); }
+
+  // Returns true, if article has a next page that is currently under
+  // distillation and that is not part of the distilled pages included in this
+  // update.
+  bool HasNextPage() const { return has_next_page_; }
+
+  // Returns true if article has a previous page that is currently under
+  // distillation and that is not part of the distilled pages included in this
+  // update.
+  bool HasPrevPage() const { return has_prev_page_; }
+
+ private:
+  bool has_next_page_;
+  bool has_prev_page_;
+  // Currently available pages.
+  std::vector<scoped_refptr<RefCountedPageProto> > pages_;
+};
+
+}  // namespace dom_distiller
+
+#endif  // COMPONENTS_DOM_DISTILLER_CORE_ARTICLE_DISTILLATION_UPDATE_H_