Simplify WebUI data sources. Currently WebUI data sources implement a URLDataSourceDelegate interfa…

content/public/browser/url_data_source_delegate.h

-// Copyright (c) 2013 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_PUBLIC_BROWSER_URL_DATA_SOURCE_DELEGATE_H_
-#define CONTENT_PUBLIC_BROWSER_URL_DATA_SOURCE_DELEGATE_H_
-
-#include <string>
-
-#include "content/common/content_export.h"
-
-class ChromeURLDataManager;
-class ChromeURLDataManagerBackend;
-class ChromeWebUIDataSource;
-class MessageLoop;
-class URLDataSource;
-
-namespace content {
-
-// An interface implemented by a creator of URLDataSource to customize its
-// behavior.
-class CONTENT_EXPORT URLDataSourceDelegate {
- public:
-  URLDataSourceDelegate();
-  virtual ~URLDataSourceDelegate();
-
-  // The name of this source.
-  // E.g., for favicons, this could be "favicon", which results in paths for
-  // specific resources like "favicon/34" getting sent to this source.
-  virtual std::string GetSource() = 0;
-
-  // Called by URLDataSource to request data at |path|.  The delegate should
-  // call URLDataSource::SendResponse() when the data is available or if the
-  // request could not be satisfied.
-  virtual void StartDataRequest(const std::string& path,
-                                bool is_incognito,
-                                int request_id) = 0;
-
-  // Return the mimetype that should be sent with this response, or empty
-  // string to specify no mime type.
-  virtual std::string GetMimeType(const std::string& path) const = 0;
-
-  // Returns the MessageLoop on which the delegate wishes to have
-  // StartDataRequest called to handle the request for |path|. The default
-  // implementation returns BrowserThread::UI. If the delegate does not care
-  // which thread StartDataRequest is called on, this should return NULL. It may
-  // be beneficial to return NULL for requests that are safe to handle directly
-  // on the IO thread.  This can improve performance by satisfying such requests
-  // more rapidly when there is a large amount of UI thread contention. Or the
-  // delegate can return a specific thread's Messageloop if they wish.
-  virtual MessageLoop* MessageLoopForRequestPath(const std::string& path) const;
-
-  // Returns true if the URLDataSource should replace an existing URLDataSource
-  // with the same name that has already been registered. The default is true.
-  //
-  // WARNING: this is invoked on the IO thread.
-  //
-  // TODO: nuke this and convert all callers to not replace.
-  virtual bool ShouldReplaceExistingSource() const;
-
-  // Returns true if responses from this URLDataSource can be cached.
-  virtual bool AllowCaching() const;
-
-  void set_url_data_source_for_testing(URLDataSource* url_data_source) {
-    url_data_source_ = url_data_source;
-  }
-
- protected:
-  URLDataSource* url_data_source() { return url_data_source_; }
-
- private:
-  friend class ::ChromeURLDataManager;
-  friend class ::ChromeURLDataManagerBackend;
-  friend class ::ChromeWebUIDataSource;
-  URLDataSource* url_data_source_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_PUBLIC_BROWSER_URL_DATA_SOURCE_DELEGATE_H_