message: Break out pc/session_description build target (part 2)
  Move the files.
  Cr-Commit-Position: refs/heads/master@{#34266}
diff: @@ -81,16 +81,6 @@ rtc_library("rtc_pc_base") {
  "sctp_transport.h",
  "sctp_utils.cc",
  "sctp_utils.h",
  -
  - # Will move to "session_description" target
  - # when downstream projects depend on that.
  - "session_description.cc",
  - "session_description.h",
  -
  - # Will move to "simulcast_description" target
  - # when downstream projects depend on that.
  - "simulcast_description.cc",
  - "simulcast_description.h",
  "srtp_filter.cc",
  "srtp_filter.h",
  "srtp_session.cc",
  @@ -187,9 +177,8 @@ rtc_library("rtc_pc_base") {
  rtc_source_set("session_description") {
  visibility = [ "*" ]
  sources = [
  - # Future home of
  - #"session_description.cc",
  - #"session_description.h",
  + "session_description.cc",
  + "session_description.h",
  ]
  deps = [
  ":media_protocol_names",
  @@ -212,9 +201,8 @@ rtc_source_set("session_description") {
  rtc_source_set("simulcast_description") {
  visibility = [ "*" ]
  sources = [
  - # Future home of
  - # "simulcast_description.cc",
  - # "simulcast_description.h",
  + "simulcast_description.cc",
  + "simulcast_description.h",
  ]
  deps = [
  "../rtc_base:checks",
  