Adding status info to DownloadUIItem and piping it through.

components/offline_pages/core/downloads/download_ui_item.h

Index: components/offline_pages/core/downloads/download_ui_item.h
diff --git a/components/offline_pages/core/downloads/download_ui_item.h b/components/offline_pages/core/downloads/download_ui_item.h
index aea7cf5ccebb9b8e8dc8d698d049b4c4051117f6..5d73f4ecd4f74c0a687a2ab96a475af4f8166890 100644
--- a/components/offline_pages/core/downloads/download_ui_item.h
+++ b/components/offline_pages/core/downloads/download_ui_item.h
@@ -18,20 +18,51 @@ namespace offline_pages {
 struct OfflinePageItem;
 class SavePageRequest;
 
+// The abstract "download item" that may be a media file, a web page (together
+// with all the resources) or a PWA web package. This is a data bag that exposes
+// only bits potentially visible by the user, not the internal data.
 struct DownloadUIItem {
  public:
+  // All Items start from PENDING and terminate at COMPLETED or are removed.
+  // In sync with state values in Java OfflinePageDownloadItem class.
+  enum DownloadState {
+    PENDING = 0,
+    DOWNLOADING = 1,
+    PAUSED = 2,
+    COMPLETED = 3,
+  };
+
+  // The abstract notion of download progress. The |current| is always less
+  // than |max|, the download 'percentage' at any moment is current/max.
+  // Note the |max| can change over time, as more resources are discovered from
+  // the bytes already loaded (which is often happening when a web page is
+  // loaded and more resources are found in the markup).
+  struct DownloadProgress {
+    DownloadProgress(int64_t current, int64_t max)
+      : current(current),
+        max(max) {}
+
+    int64_t current;
+    int64_t max;
+  };
+
   DownloadUIItem();
   explicit DownloadUIItem(const OfflinePageItem& page);
   explicit DownloadUIItem(const SavePageRequest& request);
   DownloadUIItem(const DownloadUIItem& other);
   ~DownloadUIItem();
 
-  // Unique id.
+  // Unique id. Not necesarily a GUID, may be any string unique in the Chrome
+  // instance across all DownloadUIItem providers.
   std::string guid;
 
   // The URL of the captured page.
   GURL url;
 
+  DownloadState download_state;
+
+  DownloadProgress download_progress;
+
   // The Title of the captured page, if any. It can be empty string either
   // because the page is not yet fully loaded, or because it doesn't have any.
   base::string16 title;