Rename Download Glue Implementation

> Implemented glue between UI side and native side code on both download manager path
and offline item path
> Defined API on native side for download item to excute rename
> Added DownloadRename chrome feature flag

Change-Id: I558713c37479bd0ebbf93f723e98278204580e0a
Bug: 924751
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1484617
Reviewed-by: Carlos Knippschild <[email protected]>
Reviewed-by: Elly Fong-Jones <[email protected]>
Reviewed-by: Peter Beverloo <[email protected]>
Reviewed-by: David Trainor <[email protected]>
Commit-Queue: Hesen Zhang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#640146}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 968215129..5bfb02f 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -2297,6 +2297,9 @@
 const char kDownloadHomeV2Description[] =
     "Enables the new UI for download home";
 
+const char kDownloadRenameName[] = "Enable download rename";
+const char kDownloadRenameDescription[] = "Enables rename option for downloads";
+
 const char kAutofillManualFallbackAndroidName[] =
     "Enable Autofill manual fallback for Addresses and Payments (Android)";
 const char kAutofillManualFallbackAndroidDescription[] =