Make the id used in IconMsg_DownloadFavicon unique

chrome/browser/favicon/favicon_handler_delegate.h

Index: chrome/browser/favicon/favicon_handler_delegate.h
diff --git a/chrome/browser/favicon/favicon_handler_delegate.h b/chrome/browser/favicon/favicon_handler_delegate.h
index 789f9e6f275d97900c7133da7d1e1f6a54126696..e0ff489faa9393558ab08158c538694ffdaea2e6 100644
--- a/chrome/browser/favicon/favicon_handler_delegate.h
+++ b/chrome/browser/favicon/favicon_handler_delegate.h
@@ -19,9 +19,11 @@ class FaviconHandlerDelegate {
   // Returns the current NavigationEntry.
   virtual content::NavigationEntry* GetActiveEntry() = 0;
 
-  // Starts the download for the given favicon.  When finished, the delegate
-  // will call |OnDidDownloadFavicon()| with the results.
-  virtual void StartDownload(int id, const GURL& url, int image_size) = 0;
+  // Starts the download for the given favicon. When finished, the delegate
+  // will call OnDidDownloadFavicon() with the results.
+  // Returns the unique id of the download request. The id will be passed
+  // in OnDidDownloadFavicon().
+  virtual int StartDownload(const GURL& url, int image_size) = 0;
 
   // Notifies the delegate that the favicon for the active entry was updated.
   virtual void NotifyFaviconUpdated() = 0;