Read and restore persisted slice info

content/public/browser/download_item.h

Index: content/public/browser/download_item.h
diff --git a/content/public/browser/download_item.h b/content/public/browser/download_item.h
index 32963bfd476415a5b22a75857900d68b462c7527..e6a2656eadc968557099b5330fe3fb21025aa8f2 100644
--- a/content/public/browser/download_item.h
+++ b/content/public/browser/download_item.h
@@ -102,6 +102,18 @@ class CONTENT_EXPORT DownloadItem : public base::SupportsUserData {
     virtual ~Observer() {}
   };
 
+  struct CONTENT_EXPORT ReceivedSlice {
+    ReceivedSlice(int64_t offset, int64_t received_bytes)
+        : offset(offset), received_bytes(received_bytes) {}
+
+    bool operator==(const ReceivedSlice& rhs) const {
+      return offset == rhs.offset && received_bytes == rhs.received_bytes;
+    }
+
+    int64_t offset;
+    int64_t received_bytes;
+  };
+
   ~DownloadItem() override {}
 
   // Observation ---------------------------------------------------------------
@@ -349,6 +361,10 @@ class CONTENT_EXPORT DownloadItem : public base::SupportsUserData {
   // file.
   virtual int64_t GetReceivedBytes() const = 0;
 
+  // Return the slices that have been received so far. This is only used
+  // when parallel downloading is enabled.
+  virtual const std::vector<ReceivedSlice>& GetReceivedSlices() const = 0;
+
   // Time the download was first started. This timestamp is always valid and
   // doesn't change.
   virtual base::Time GetStartTime() const = 0;