Don't delete CopyOutputRequests when queueing a new Surface frame.

cc/surfaces/surface.h

Index: cc/surfaces/surface.h
diff --git a/cc/surfaces/surface.h b/cc/surfaces/surface.h
index c42292e3b04655cf1f97498df3ab5acfcfd5f397..3901d2c2c17b71877f32ea955233b73d84550cc0 100644
--- a/cc/surfaces/surface.h
+++ b/cc/surfaces/surface.h
@@ -121,6 +121,8 @@ class CC_SURFACES_EXPORT Surface {
   bool destroyed() const { return destroyed_; }
   void set_destroyed(bool destroyed) { destroyed_ = destroyed; }
 
+  bool HasRootCopyRequests() const { return !copy_requests_.empty(); }
+
  private:
   void ActivatePendingFrame();
   // Called when all of the surface's dependencies have been resolved.
@@ -141,6 +143,7 @@ class CC_SURFACES_EXPORT Surface {
   int frame_index_;
   bool destroyed_;
   std::vector<SurfaceSequence> destruction_dependencies_;
+  std::vector<std::unique_ptr<CopyOutputRequest>> copy_requests_;
 
   // This surface may have multiple BeginFrameSources if it is
   // on multiple Displays.