Context menus should appear above the touch point if invoked by long press.

content/browser/web_contents/web_contents_view_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <Carbon/Carbon.h>
 
 #import "content/browser/web_contents/web_contents_view_mac.h"
 
 #include <string>
 
@@ skipping 263 matching lines @@
 // iterated past the last focusable element on the page).
 void WebContentsViewMac::TakeFocus(bool reverse) {
   if (reverse) {
     [[cocoa_view_ window] selectPreviousKeyView:cocoa_view_.get()];
   } else {
     [[cocoa_view_ window] selectNextKeyView:cocoa_view_.get()];
   }
 }
 
 void WebContentsViewMac::ShowContextMenu(
-    const content::ContextMenuParams& params) {
+    const content::ContextMenuParams& params,
+    const content::ContextMenuSourceType& type) {
   // Allow delegates to handle the context menu operation first.
   if (web_contents_->GetDelegate() &&
       web_contents_->GetDelegate()->HandleContextMenu(params)) {
     return;
   }
 
   if (delegate())
-    delegate()->ShowContextMenu(params);
+    delegate()->ShowContextMenu(params, type);
   else
     DLOG(ERROR) << "Cannot show context menus without a delegate.";
 }
 
 // Display a popup menu for WebKit using Cocoa widgets.
 void WebContentsViewMac::ShowPopupMenu(
     const gfx::Rect& bounds,
     int item_height,
     double item_font_size,
     int selected_item,
@@ skipping 226 matching lines @@
       [[[notification userInfo] objectForKey:kSelectionDirection]
         unsignedIntegerValue];
   if (direction == NSDirectSelection)
     return;
 
   [self webContents]->
       FocusThroughTabTraversal(direction == NSSelectingPrevious);
 }
 
 @end