DragEnter grants both read and navigate permissions to files.

content/browser/renderer_host/render_view_host_impl.cc

 // 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.
 
 #include "content/browser/renderer_host/render_view_host_impl.h"
 
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 559 matching lines @@
   const int renderer_id = GetProcess()->GetID();
   ChildProcessSecurityPolicyImpl* policy =
       ChildProcessSecurityPolicyImpl::GetInstance();
 
   // The URL could have been cobbled together from any highlighted text string,
   // and can't be interpreted as a capability.
   WebDropData filtered_data(drop_data);
   FilterURL(policy, renderer_id, true, &filtered_data.url);
 
   // The filenames vector, on the other hand, does represent a capability to
-  // access the given files.
+  // read the given files (but not to navigate to any file:// scheme URL),
   std::set<FilePath> filesets;
   for (std::vector<WebDropData::FileInfo>::const_iterator iter(
            filtered_data.filenames.begin());
        iter != filtered_data.filenames.end(); ++iter) {
     FilePath path = FilePath::FromUTF8Unsafe(UTF16ToUTF8(iter->path));
-    policy->GrantRequestURL(renderer_id, net::FilePathToFileURL(path));
 
     // If the renderer already has permission to read these paths, we don't need
     // to re-grant them. This prevents problems with DnD for files in the CrOS
     // file manager--the file manager already had read/write access to those
     // directories, but dragging a file would cause the read/write access to be
     // overwritten with read-only access, making them impossible to delete or
     // rename until the renderer was killed.
     if (!policy->CanReadFile(renderer_id, path)) {
       policy->GrantReadFile(renderer_id, path);
       // Allow dragged directories to be enumerated by the child process.
@@ skipping 1279 matching lines @@
   is_waiting_for_beforeunload_ack_ = false;
   is_waiting_for_unload_ack_ = false;
   has_timed_out_on_unload_ = false;
 }
 
 void RenderViewHostImpl::ClearPowerSaveBlockers() {
   STLDeleteValues(&power_save_blockers_);
 }
 
 }  // namespace content