Build WebRTC with data channel only.

webrtc/sdk/android/BUILD.gn

Index: webrtc/sdk/android/BUILD.gn
diff --git a/webrtc/sdk/android/BUILD.gn b/webrtc/sdk/android/BUILD.gn
index 9fcedf907b7a5ce823aba7d243ef468c458179b3..d7ae716a1fa1ee6b886ac20dfcf401f5bf4fd320 100644
--- a/webrtc/sdk/android/BUILD.gn
+++ b/webrtc/sdk/android/BUILD.gn
@@ -26,10 +26,6 @@ rtc_static_library("libjingle_peerconnection_jni") {
   sources = [
     "src/jni/androidhistogram_jni.cc",
     "src/jni/androidmediacodeccommon.h",
-    "src/jni/androidmediadecoder_jni.cc",
-    "src/jni/androidmediadecoder_jni.h",
-    "src/jni/androidmediaencoder_jni.cc",
-    "src/jni/androidmediaencoder_jni.h",
     "src/jni/androidnetworkmonitor_jni.cc",
     "src/jni/androidnetworkmonitor_jni.h",
     "src/jni/androidvideotracksource.cc",
@@ -70,18 +66,14 @@ rtc_static_library("libjingle_peerconnection_jni") {
 
   deps = [
     "../..:webrtc_common",
-    "../../api:video_frame_api",
     "../../api/video_codecs:video_codecs_api",
     "../../base:rtc_base",
     "../../base:rtc_base_approved",
     "../../base:rtc_task_queue",
-    "../../common_video:common_video",
     "../../media:rtc_media",
     "../../media:rtc_media_base",
     "../../modules/utility:utility",
-    "../../modules/video_coding:video_coding_utility",
     "../../system_wrappers:system_wrappers",
-    "../../voice_engine:voice_engine",
     "//webrtc/pc:libjingle_peerconnection",
   ]
 
@@ -94,6 +86,22 @@ rtc_static_library("libjingle_peerconnection_jni") {
     # Need to add a directory normally exported by libyuv.
     include_dirs = [ "$rtc_libyuv_dir/include" ]
   }
+
+  if (rtc_enable_media) {
+    sources += [
+      "src/jni/androidmediadecoder_jni.cc",
+      "src/jni/androidmediadecoder_jni.h",
+      "src/jni/androidmediaencoder_jni.cc",
+      "src/jni/androidmediaencoder_jni.h",
+    ]
+
+    deps += [
+      "../../api:video_frame_api",
+      "../../common_video:common_video",
+      "../../modules/video_coding:video_coding_utility",
+      "../../voice_engine:voice_engine",
+    ]
+  }
 }
 
 rtc_static_library("libjingle_peerconnection_metrics_default_jni") {