Move AudioRenderer out of Filter heirarchy.

media/base/callback_util.cc

+// 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.
+
+#include "media/base/callback_util.h"
+
+#include "base/bind.h"
+#include "base/memory/ref_counted.h"
+
+namespace media {
+
+namespace {

[acolwell GONE FROM CHROMIUM, 2012/07/19 00:58:18]

remove per our discussion.

[scherkus (not reviewing), 2012/07/19 21:29:02]

Done.

+
+// Executes a callback when all references to the object have been
+// released. We use reference counting as it already implements a thread safe
+// counter and avoids the use of base::Unretained() and delete this, which may
+// lead to use-after-free if clients retain closures after executing them.
+class CountingCB : public base::RefCountedThreadSafe<CountingCB> {
+ public:
+  CountingCB(const base::Closure& done_cb)

[acolwell GONE FROM CHROMIUM, 2012/07/19 00:58:18]

explicit

[scherkus (not reviewing), 2012/07/19 21:29:02]

Done.

+      : done_cb_(done_cb) {
+  }
+
+  // Returns a closure bound to this object.
+  base::Closure GetClosure() {
+    return base::Bind(&CountingCB::DoNothing, this);
+  }
+
+ protected:
+  friend class base::RefCountedThreadSafe<CountingCB>;
+  virtual ~CountingCB() {
+    done_cb_.Run();
+  }
+
+ private:
+  void DoNothing() {}
+
+  base::Closure done_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(CountingCB);
+};
+
+}  // namespace
+
+void RunInSeries(scoped_ptr<std::queue<ClosureCB> > closures,
+                 const base::Closure& done_cb) {
+  if (closures->empty()) {
+    done_cb.Run();
+    return;
+  }
+
+  ClosureCB cb = closures->front();
+  closures->pop();
+  cb.Run(base::Bind(&RunInSeries, base::Passed(&closures), done_cb));
+}
+
+void RunInParallel(scoped_ptr<std::queue<ClosureCB> > closures,
+                   const base::Closure& done_cb) {
+  scoped_refptr<CountingCB> counting_cb = new CountingCB(done_cb);
+  while (!closures->empty()) {
+    closures->front().Run(counting_cb->GetClosure());
+    closures->pop();
+  }
+}
+
+}  // namespace media