Fix most of the downloads api in incognito profiles

chrome/browser/download/download_extension_api.h

Index: chrome/browser/download/download_extension_api.h
diff --git a/chrome/browser/download/download_extension_api.h b/chrome/browser/download/download_extension_api.h
index 8eba05e62ec8120fef992d09b576f50038d7bc15..9cf95f4f7dfdef600c59268c3480b20cfbe4638a 100644
--- a/chrome/browser/download/download_extension_api.h
+++ b/chrome/browser/download/download_extension_api.h
@@ -93,6 +93,8 @@ class SyncDownloadsFunction : public SyncExtensionFunction,
   // DownloadsFunctionInterface:
   virtual DownloadsFunctionName function() const OVERRIDE;
 
+  content::DownloadItem* GetActiveItem(int download_id);
+
  private:
   DownloadsFunctionName function_;
 
@@ -111,6 +113,8 @@ class AsyncDownloadsFunction : public AsyncExtensionFunction,
   // DownloadsFunctionInterface:
   virtual DownloadsFunctionName function() const OVERRIDE;
 
+  content::DownloadItem* GetActiveItem(int download_id);
+
  private:
   DownloadsFunctionName function_;