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..c5915087e23bb82d70abcbe7ffb36f0865778e98 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",
@@ -39,13 +35,9 @@ rtc_static_library("libjingle_peerconnection_jni") {
     "src/jni/classreferenceholder.h",
     "src/jni/jni_helpers.cc",
     "src/jni/jni_helpers.h",
-    "src/jni/native_handle_impl.cc",
-    "src/jni/native_handle_impl.h",
     "src/jni/peerconnection_jni.cc",
     "src/jni/rtcstatscollectorcallbackwrapper.cc",
     "src/jni/rtcstatscollectorcallbackwrapper.h",
-    "src/jni/surfacetexturehelper_jni.cc",
-    "src/jni/surfacetexturehelper_jni.h",
   ]
 
   configs += [ ":libjingle_peerconnection_jni_warnings_config" ]
@@ -69,21 +61,78 @@ rtc_static_library("libjingle_peerconnection_jni") {
   }
 
   deps = [
+    ":libjingle_peerconnection_audio_jni",
+    ":libjingle_peerconnection_video_jni",
     "../..: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_audio_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",
   ]
+}
+
+rtc_static_library("libjingle_peerconnection_audio_jni") {

[Zhi Huang, 2017/05/18 03:55:39]

These are the top level target which the application can use to build .so file.

+  deps = [
+    "../../voice_engine:voice_engine",
+    "//webrtc/pc:libjingle_peerconnection_audio",
+    "//webrtc/pc:libjingle_peerconnection_media",
+  ]
+}
+
+rtc_static_library("libjingle_peerconnection_audio_nullimpl_jni") {

[Zhi Huang, 2017/05/18 03:55:38]

These are the top level target which the application can use to build .so file.

Use this when build without audio.

+  deps = [
+    "//webrtc/pc:libjingle_peerconnection_audio_nullimpl",
+    "//webrtc/pc:libjingle_peerconnection_media_nullimpl",
+    "//webrtc/pc:rtc_pc_audio_nullimpl",
+  ]
+}
+
+rtc_static_library("libjingle_peerconnection_video_jni") {

[Zhi Huang, 2017/05/18 03:55:38]

Similar to audio.

+  sources = [
+    "src/jni/androidmediadecoder_jni.cc",
+    "src/jni/androidmediadecoder_jni.h",
+    "src/jni/androidmediaencoder_jni.cc",
+    "src/jni/androidmediaencoder_jni.h",
+    "src/jni/native_handle_impl.cc",
+    "src/jni/native_handle_impl.h",
+    "src/jni/peerconnection_video_jni.cc",
+    "src/jni/surfacetexturehelper_jni.cc",
+    "src/jni/surfacetexturehelper_jni.h",
+    "src/jni/video_renderer_jni.cc",
+  ]
+
+  configs += [ ":libjingle_peerconnection_jni_warnings_config" ]
+
+  if (is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+    suppressed_configs += [
+      "//build/config/clang:extra_warnings",
+      "//build/config/clang:find_bad_constructs",
+    ]
+  }
+
+  # TODO(jschuh): Bug 1348: fix this warning.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
+
+  if (is_win) {
+    cflags += [
+      "/wd4245",  # conversion from "int" to "size_t", signed/unsigned mismatch.
+      "/wd4389",  # signed/unsigned mismatch.
+    ]
+  }
+
+  deps = [
+    "../../api:video_frame_api",
+    "../../api/video_codecs:video_codecs_api",
+    "../../common_video:common_video",
+    "../../modules/video_coding:video_coding_utility",
+    "//webrtc/pc:libjingle_peerconnection_media",
+  ]
 
   if (rtc_build_libyuv) {
     deps += [ "$rtc_libyuv_dir" ]
@@ -96,6 +145,81 @@ rtc_static_library("libjingle_peerconnection_jni") {
   }
 }
 
+rtc_static_library("libjingle_peerconnection_video_nullimpl_jni") {
+  sources = [
+    "src/jni/peerconnection_video_nullimpl_jni.cc",
+  ]
+
+  deps = [
+    "//webrtc/media:rtc_media_video_base_nullimpl",
+    "//webrtc/pc:libjingle_peerconnection_media_nullimpl",
+  ]
+}
+
+rtc_static_library("libjingle_peerconnection_base_jni") {

[Zhi Huang, 2017/05/18 03:55:38]

The target without audio and video.

+  sources = [
+    "src/jni/androidhistogram_jni.cc",
+    "src/jni/androidmediacodeccommon.h",
+    "src/jni/androidnetworkmonitor_jni.cc",
+    "src/jni/androidnetworkmonitor_jni.h",
+    "src/jni/classreferenceholder.cc",
+    "src/jni/classreferenceholder.h",
+    "src/jni/jni_helpers.cc",
+    "src/jni/jni_helpers.h",
+    "src/jni/peerconnection_jni.cc",
+    "src/jni/rtcstatscollectorcallbackwrapper.cc",
+    "src/jni/rtcstatscollectorcallbackwrapper.h",
+  ]
+
+  configs += [ ":libjingle_peerconnection_jni_warnings_config" ]
+
+  if (is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+    suppressed_configs += [
+      "//build/config/clang:extra_warnings",
+      "//build/config/clang:find_bad_constructs",
+    ]
+  }
+
+  # TODO(jschuh): Bug 1348: fix this warning.
+  configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
+
+  if (is_win) {
+    cflags += [
+      "/wd4245",  # conversion from "int" to "size_t", signed/unsigned mismatch.
+      "/wd4389",  # signed/unsigned mismatch.
+    ]
+  }
+
+  deps = [
+    "../..:webrtc_common",
+    "../../base:rtc_base",
+    "../../base:rtc_base_approved",
+    "../../base:rtc_task_queue",
+    "../../media:rtc_media",
+    "../../media:rtc_media_base",
+    "../../modules/utility:utility",
+    "../../system_wrappers:system_wrappers",
+    "//webrtc/pc:libjingle_peerconnection_base",
+  ]
+}
+
+rtc_static_library("libjingle_peerconnection_base_metrics_default_jni") {
+  sources = [
+    "src/jni/androidmetrics_jni.cc",
+  ]
+
+  configs += [ ":libjingle_peerconnection_jni_warnings_config" ]
+
+  deps = [
+    ":libjingle_peerconnection_base_jni",
+    "../../system_wrappers",
+    "//webrtc/pc:libjingle_peerconnection_base",
+    "//webrtc/system_wrappers:field_trial_default",
+    "//webrtc/system_wrappers:metrics_default",
+  ]
+}
+
 rtc_static_library("libjingle_peerconnection_metrics_default_jni") {
   sources = [
     "src/jni/androidmetrics_jni.cc",
@@ -112,6 +236,25 @@ rtc_static_library("libjingle_peerconnection_metrics_default_jni") {
   ]
 }
 
+rtc_shared_library("libjingle_peerconnection_datachannel_only_so") {

[Zhi Huang, 2017/05/18 03:55:38]

This is just an example of how to use these targets.

We can force the internal application to create something like this.

+  sources = [
+    "src/jni/jni_onload.cc",
+  ]
+
+  suppressed_configs += [ "//build/config/android:hide_all_but_jni_onload" ]
+  configs += [ "//build/config/android:hide_all_but_jni" ]
+
+  deps = [
+    ":libjingle_peerconnection_audio_nullimpl_jni",
+    ":libjingle_peerconnection_base_jni",
+    ":libjingle_peerconnection_base_metrics_default_jni",
+    ":libjingle_peerconnection_video_nullimpl_jni",
+    "../../base:rtc_base",
+    "//webrtc/pc:libjingle_peerconnection_base",
+  ]
+  output_extension = "so"
+}
+
 rtc_shared_library("libjingle_peerconnection_so") {
   sources = [
     "src/jni/jni_onload.cc",