[Downloads] Introduce GUIDs for downloads.

components/history/core/browser/download_row.h

Index: components/history/core/browser/download_row.h
diff --git a/components/history/core/browser/download_row.h b/components/history/core/browser/download_row.h
index 98304519ce6f26488b2a98dc97fa3df90006582a..3127c3f3d6cd1578542bcab0ee6a9e319d106a86 100644
--- a/components/history/core/browser/download_row.h
+++ b/components/history/core/browser/download_row.h
@@ -26,6 +26,7 @@ struct DownloadRow {
               const base::FilePath& target_path,
               const std::vector<GURL>& url_chain,
               const GURL& referrer,
+              const std::string& http_method,
               const std::string& mime_type,
               const std::string& original_mime_type,
               const base::Time& start,
@@ -37,13 +38,17 @@ struct DownloadRow {
               DownloadState download_state,
               DownloadDangerType danger_type,
               DownloadInterruptReason interrupt_reason,
+              const std::string& hash,
               DownloadId id,
+              const std::string& guid,
               bool download_opened,
               const std::string& ext_id,
               const std::string& ext_name);
   DownloadRow(const DownloadRow& other);
   ~DownloadRow();
 
+  bool operator==(const DownloadRow&) const;
+
   // The current path to the download (potentially different from final if
   // download is in progress or interrupted).
   base::FilePath current_path;
@@ -60,6 +65,10 @@ struct DownloadRow {
   // The URL that referred us. Is not changed by UpdateDownload().
   GURL referrer_url;
 
+  // HTTP method used for the request. GET is assumed if the method was not
+  // stored for a download in the history database.
+  std::string http_method;
+
   // The MIME type of the download, might be based on heuristics.
   std::string mime_type;
 
@@ -94,9 +103,18 @@ struct DownloadRow {
   // The reason the download was interrupted, if state == kStateInterrupted.
   DownloadInterruptReason interrupt_reason;
 
+  // The raw SHA-256 hash of the complete or partial download contents. Not hex
+  // encoded.
+  std::string hash;
+
   // The id of the download in the database. Is not changed by UpdateDownload().
+  // Note: This field should be considered deprecated in favor of |guid| below.
+  // See http://crbug.com/593020.
   DownloadId id;
 
+  // The GUID of the download in the database. Not changed by UpdateDownload().
+  std::string guid;
+
   // Whether this download has ever been opened from the browser.
   bool opened;