Reland r187230: Implement the Stream registry in content

content/browser/streams/stream_context.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_BROWSER_STREAMS_STREAM_CONTEXT_H_
+#define CONTENT_BROWSER_STREAMS_STREAM_CONTEXT_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/sequenced_task_runner_helpers.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+class BrowserContext;
+class StreamRegistry;
+struct StreamContextDeleter;
+
+// A context class that keeps track of StreamRegistry used by the chrome.
+// There is an instance associated with each BrowserContext. There could be
+// multiple URLRequestContexts in the same browser context that refers to the
+// same instance.
+//
+// All methods, except the ctor, are expected to be called on
+// the IO thread (unless specifically called out in doc comments).
+class StreamContext
+    : public base::RefCountedThreadSafe<StreamContext,
+                                        StreamContextDeleter> {
+ public:
+  StreamContext();
+
+  static StreamContext* GetFor(BrowserContext* browser_context);
+
+  void InitializeOnIOThread();
+
+  StreamRegistry* registry() const { return registry_.get(); }
+
+ protected:
+  virtual ~StreamContext();
+
+ private:
+  friend class base::DeleteHelper<StreamContext>;
+  friend class base::RefCountedThreadSafe<StreamContext,
+                                          StreamContextDeleter>;
+  friend struct StreamContextDeleter;
+
+  void DeleteOnCorrectThread() const;
+
+  scoped_ptr<StreamRegistry> registry_;
+};
+
+struct StreamContextDeleter {
+  static void Destruct(const StreamContext* context) {
+    context->DeleteOnCorrectThread();
+  }
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_STREAMS_STREAM_CONTEXT_H_
+