RTPFragmentationHeader::VerifyAndAllocateFragmentationHeader: Verify that size fits in 16 bits
RTPFragmentationHeader::VerifyAndAllocateFragmentationHeader: Verify that size fits in 16 bits

This CL change the function declaration from uint16_t to size_t, and CHECKs that the size fits in uint16_t before proceeding.

BUG=484432
R=tommi@webrtc.org

Committed: https://crrev.com/10022cdeae785187e1d4329042b4ed294c393a16
Cr-Commit-Position: refs/heads/master@{#9246}

Review URL: https://webrtc-codereview.appspot.com/47229004

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#9253}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: a3ba0c7f5a347ec310ffa95efdf078950134abd5

Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk,sippet/webrtc,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,krieger-od/webrtc,sippet/webrtc,krieger-od/webrtc,Alkalyne/webrtctrunk,sippet/webrtc,krieger-od/webrtc,sippet/webrtc,jchavanton/webrtc,aleonliao/webrtc-trunk,jchavanton/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,sippet/webrtc,jchavanton/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk,krieger-od/webrtc,jchavanton/webrtc,sippet/webrtc,krieger-od/webrtc,Alkalyne/webrtctrunk,jchavanton/webrtc,krieger-od/webrtc