cc: Add CopyAsBitmapRequest class to hold the readback callback.

cc/output/copy_output_request.cc

Index: cc/output/copy_output_request.cc
diff --git a/cc/output/copy_output_request.cc b/cc/output/copy_output_request.cc
new file mode 100644
index 0000000000000000000000000000000000000000..437cce546abe040bd2a7be69d2a16bc5032eaf67
--- /dev/null
+++ b/cc/output/copy_output_request.cc
@@ -0,0 +1,30 @@
+// Copyright 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.
+
+#include "cc/output/copy_output_request.h"
+
+#include "base/callback_helpers.h"
+#include "base/logging.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+namespace cc {
+
+CopyOutputRequest::CopyOutputRequest(const CopyAsBitmapCallback& callback)
+    : bitmap_callback_(callback) {}
+
+CopyOutputRequest::~CopyOutputRequest() {
+  SendEmptyResult();
+}
+
+void CopyOutputRequest::SendEmptyResult() {
+  if (!bitmap_callback_.is_null())
+    base::ResetAndReturn(&bitmap_callback_).Run(scoped_ptr<SkBitmap>());
+}
+
+void CopyOutputRequest::SendBitmapResult(scoped_ptr<SkBitmap> bitmap) {
+  DCHECK(HasBitmapRequest());
+  base::ResetAndReturn(&bitmap_callback_).Run(bitmap.Pass());
+}
+
+}  // namespace cc