Break out media_stream_observer.cc in peerconnection build

Bug: webrtc:13634
Change-Id: Ie1368217bc3735b0a747c39dbbb5afbc929c4cf3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250080
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35867}

pc/BUILD.gn

@@ -244,8 +244,6 @@ rtc_library("peerconnection") {
     "jsep_session_description.cc",
     "local_audio_source.cc",
     "local_audio_source.h",
-    "media_stream_observer.cc",
-    "media_stream_observer.h",
     "peer_connection.cc",
     "peer_connection.h",
     "peer_connection_factory.cc",
@@ -440,7 +438,19 @@ rtc_source_set("ice_server_parsing") {
   visibility = [ "*" ]  # Known to be used externally
 }
 rtc_source_set("media_stream_observer") {
-  visibility = [ ":*" ]
+  visibility = [
+    ":*",
+    "../sdk/android:*",
+  ]
+  sources = [
+    "media_stream_observer.cc",
+    "media_stream_observer.h",
+  ]
+  deps = [
+    "../api:media_stream_interface",
+    "../api:scoped_refptr",
+  ]
+  absl_deps = [ "//third_party/abseil-cpp/absl/algorithm:container" ]
 }
 rtc_source_set("peer_connection_factory") {
   visibility = [ "*" ]  # Known to be used externally

sdk/android/BUILD.gn

@@ -794,6 +794,7 @@ if (current_os == "linux" || is_android) {
       "../../modules/audio_device",
       "../../modules/audio_processing:api",
       "../../modules/utility",
+      "../../pc:media_stream_observer",
       "../../pc:peerconnection",
       "../../rtc_base",
       "../../rtc_base:checks",