Introduce a new WebChannel option 'encodeInitMessageHeaders'. RELNOTES: none
Introduce a new WebChannel option 'encodeInitMessageHeaders'.
RELNOTES: none

PiperOrigin-RevId: 396147413
Change-Id: Ic94318fbcf0fbc9fc4fe0930689c495353f22146

google/closure-library,google/closure-library,google/closure-library,google/closure-library,google/closure-library