cc: Add CopyAsBitmapRequest class to hold the readback callback.

cc/output/copy_output_request.h

Index: cc/output/copy_output_request.h
diff --git a/cc/output/copy_output_request.h b/cc/output/copy_output_request.h
new file mode 100644
index 0000000000000000000000000000000000000000..d0ef48b3809a912af89d1837784cc9feeb680ec7
--- /dev/null
+++ b/cc/output/copy_output_request.h
@@ -0,0 +1,45 @@
+// 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.
+
+#ifndef CC_OUTPUT_COPY_OUTPUT_REQUEST_H_
+#define CC_OUTPUT_COPY_OUTPUT_REQUEST_H_
+
+#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"
+#include "cc/base/cc_export.h"
+
+class SkBitmap;
+
+namespace cc {
+
+class CC_EXPORT CopyOutputRequest {
+ public:
+  typedef base::Callback<void(scoped_ptr<SkBitmap>)> CopyAsBitmapCallback;
+
+  static scoped_ptr<CopyOutputRequest> CreateBitmapRequest(
+      const CopyAsBitmapCallback& bitmap_callback) {
+    return make_scoped_ptr(new CopyOutputRequest(bitmap_callback));
+  }
+
+  ~CopyOutputRequest();
+
+  bool IsEmpty() const { return !HasBitmapRequest(); }
+  bool HasBitmapRequest() const { return !bitmap_callback_.is_null(); }
+
+  void SendEmptyResult();
+  void SendBitmapResult(scoped_ptr<SkBitmap> bitmap);
+
+  bool Equals(const CopyOutputRequest& other) const {
+    return bitmap_callback_.Equals(other.bitmap_callback_);
+  }
+
+ private:
+  explicit CopyOutputRequest(const CopyAsBitmapCallback& callback);
+
+  CopyAsBitmapCallback bitmap_callback_;
+};
+
+}  // namespace cc
+
+#endif  // CC_OUTPUT_COPY_OUTPUT_REQUEST_H_