Don't derive from ChromeURLDataManager::DataSource, and instead have these classes implement a dele…

content/public/browser/url_data_source_delegate.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.

[James Hawkins, 2013/01/14 19:24:33]

Fix linter issues in this file.

[jam, 2013/01/14 20:25:14]

Done.

+// 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_