[DragDrop] Add feature flag to control context menu anchor

Bug: 1261249
Change-Id: I49f808eca32d8db80bb221fb9791526acb3e68b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3230234
Commit-Queue: Wenyu Fu <[email protected]>
Auto-Submit: Wenyu Fu <[email protected]>
Reviewed-by: Theresa  <[email protected]>
Cr-Commit-Position: refs/heads/main@{#933689}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 5653b3c4..63f8ef1 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3058,6 +3058,11 @@
     "A new method of persisting Tab data across restarts has been devised "
     "and implemented. This actives the new approach.";
 
+const char kContextMenuPopupStyleName[] = "Context menu popup style";
+const char kContextMenuPopupStyleDescription[] =
+    "Enable the popup style context menu, where the context menu will be"
+    "anchored around the touch point.";
+
 const char kContextualSearchDebugName[] = "Contextual Search debug";
 const char kContextualSearchDebugDescription[] =
     "Enables internal debugging of Contextual Search behavior on the client "