Move font_list_async.h to content/public. Switch to Pass() goodness to simplify code.

content/browser/font_list_async.h

-// Copyright (c) 2011 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.
-
-#ifndef CONTENT_BROWSER_FONT_LIST_ASYNC_H_
-#define CONTENT_BROWSER_FONT_LIST_ASYNC_H_
-
-#include "base/callback_forward.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "content/common/content_export.h"
-
-namespace base {
-class ListValue;
-}
-
-namespace content {
-
-// Wraps ownership of a ListValue so we can send it across threads without
-// having ownership problems (for example if the calling thread goes away
-// before the callback is executed, we want the ListValue to be destroyed.
-struct CONTENT_EXPORT FontListResult
-    : public base::RefCountedThreadSafe<FontListResult> {
-  FontListResult();
-  ~FontListResult();
-
-  scoped_ptr<base::ListValue> list;
-};
-
-// Retrieves the list of fonts on the system as a list of strings. It provides
-// a non-blocking interface to GetFontList_SlowBlocking in common/.
-//
-// This function will run asynchronously on a background thread since getting
-// the font list from the system can be slow. This function may be called from
-// any thread that has a BrowserThread::ID. The callback will be executed on
-// the calling thread.
-//
-// If the caller wants to take ownership of the ListValue, it can just do
-// FontListResult.list.release() or use scoped_ptr.swap() because this value
-// isn't used for anything else.
-CONTENT_EXPORT void GetFontListAsync(
-    const base::Callback<void(scoped_refptr<FontListResult>)>& callback);
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_FONT_LIST_ASYNC_H_