Modifying buffers passed in to the frame buffer breaks sharing. This cl is also a preparation for deleting VCMEncodedFrame::VerifyAndAllocate and EncodedImage::Allocate. Bug: None Change-Id: I4e14bc4708bbcbcd91af2d4b764cb9b8271ec090 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/154569 Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org> Reviewed-by: Philip Eliasson <philipel@webrtc.org> Commit-Queue: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/master@{#29336}