Move PathExists to base namespace.

content/browser/web_contents/web_drag_source_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 "content/browser/web_contents/web_drag_source_mac.h"
 
 #include <sys/param.h>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 351 matching lines @@
 - (void)writePromisedFileTo:(NSString*)path {
   // Be extra paranoid; avoid crashing.
   if (!dropData_) {
     NOTREACHED() << "No drag-and-drop data available for promised file.";
     return;
   }
 
   base::FilePath filePath(SysNSStringToUTF8(path));
   filePath = filePath.Append(downloadFileName_);
 
-  // CreateFileStreamForDrop() will call file_util::PathExists(),
+  // CreateFileStreamForDrop() will call base::PathExists(),
   // which is blocking.  Since this operation is already blocking the
   // UI thread on OSX, it should be reasonable to let it happen.
   base::ThreadRestrictions::ScopedAllowIO allowIO;
   scoped_ptr<FileStream> fileStream(content::CreateFileStreamForDrop(
       &filePath, content::GetContentClient()->browser()->GetNetLog()));
   if (!fileStream)
     return;
 
   if (downloadURL_.is_valid()) {
     scoped_refptr<DragDownloadFile> dragFileDownloader(new DragDownloadFile(
@@ skipping 118 matching lines @@
 - (NSImage*)dragImage {
   if (dragImage_)
     return dragImage_;
 
   // Default to returning a generic image.
   return content::GetContentClient()->GetNativeImageNamed(
       IDR_DEFAULT_FAVICON).ToNSImage();
 }
 
 @end  // @implementation WebDragSource (Private)