Added member data to classes to support download resumption.

content/browser/download/base_file.h

Index: content/browser/download/base_file.h
diff --git a/content/browser/download/base_file.h b/content/browser/download/base_file.h
index 8fbcdd0a9d1f79b0d868a5ec91e2b1db7ffb4330..c6e32ee544f6d2d0e2d66bf7b7dcf03c73a563ee 100644
--- a/content/browser/download/base_file.h
+++ b/content/browser/download/base_file.h
@@ -32,6 +32,7 @@ class CONTENT_EXPORT BaseFile {
            const GURL& source_url,
            const GURL& referrer_url,
            int64 received_bytes,
+           const std::string& initial_hash,
            const linked_ptr<net::FileStream>& file_stream);
   virtual ~BaseFile();
 
@@ -64,7 +65,7 @@ class CONTENT_EXPORT BaseFile {
   bool in_progress() const { return file_stream_ != NULL; }
   int64 bytes_so_far() const { return bytes_so_far_; }
 
-  // Set |hash| with sha256 digest for the file.
+  // Fills |hash| with the sha256 digest for the file.  May be partial.
   // Returns true if digest is successfully calculated.
   virtual bool GetSha256Hash(std::string* hash);