Detect removed files and reflect the state in chrome://downloads and the download shelf

chrome/browser/ui/browser.h

Index: chrome/browser/ui/browser.h
diff --git a/chrome/browser/ui/browser.h b/chrome/browser/ui/browser.h
index d3863b91c0e1bad702a70caf861830dc77e1f55d..71e217236ff80bb18dc9da932199b8b668421916 100644
--- a/chrome/browser/ui/browser.h
+++ b/chrome/browser/ui/browser.h
@@ -649,6 +649,11 @@ class Browser : public TabHandlerDelegate,
                                   PageTransition::Type transition,
                                   bool user_initiated);
 
+  // Checks whether downloaded files still exist. Updates state of downloads
+  // that refer to removed files. The check runs in the background and may
+  // finish asynchronously after this method returns.
+  void CheckForFilesRemoval();
+
   // Called by browser::Navigate() to retrieve the home page if no URL is
   // specified.
   GURL GetHomePage() const;