MojoCompositorFrameSinkPrivate should support copy requests

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
index 112daa40dcefe08ad0b4c567badf096b378e2778..8d8c0621f849a41b726de1b996dcbb109ab5ed25 100644
--- a/cc/output/copy_output_request.h
+++ b/cc/output/copy_output_request.h
@@ -74,6 +74,13 @@ class CC_EXPORT CopyOutputRequest {
   bool has_texture_mailbox() const { return texture_mailbox_.has_value(); }
   const TextureMailbox& texture_mailbox() const { return *texture_mailbox_; }
 
+  void set_result_callback(CopyOutputRequestCallback result_callback) {

[Fady Samuel, 2017/02/15 13:32:20]

Is this still necessary? Thanks!

[Saman Sami, 2017/02/15 22:53:56]

Not after my other CL lands. I'll get rid of it.

+    result_callback_ = result_callback;
+  }
+  const CopyOutputRequestCallback& result_callback() {
+    return result_callback_;
+  }
+
   void SendEmptyResult();
   void SendBitmapResult(std::unique_ptr<SkBitmap> bitmap);
   void SendTextureResult(