Build WebRTC with data channel only.

webrtc/pc/BUILD.gn

Index: webrtc/pc/BUILD.gn
diff --git a/webrtc/pc/BUILD.gn b/webrtc/pc/BUILD.gn
index 10256ce2f407cc3b76e5ee3c28dfbde8188536be..0040379d0beb673610688f7fed6c84c4eadee56c 100644
--- a/webrtc/pc/BUILD.gn
+++ b/webrtc/pc/BUILD.gn
@@ -25,7 +25,7 @@ config("rtc_pc_config") {
   }
 }
 
-rtc_static_library("rtc_pc") {
+rtc_static_library("rtc_pc_base") {
   defines = []
   sources = [
     "audiomonitor.cc",
@@ -59,8 +59,9 @@ rtc_static_library("rtc_pc") {
     "../api:libjingle_peerconnection_api",
     "../api:ortc_api",
     "../base:rtc_base",
-    "../common_video:common_video",
-    "../media",
+    "../base:rtc_task_queue",
+    "../media:rtc_data",
+    "../media:rtc_media_base_data",
     "../p2p:rtc_p2p",
   ]
 
@@ -76,6 +77,18 @@ rtc_static_library("rtc_pc") {
   }
 }
 
+# TODO(zhihuang): Remove this once the downstream dependencies start using the
+# modular targets.
+rtc_source_set("rtc_pc") {
+  public_deps = [
+    ":rtc_pc_base",
+  ]
+
+  deps = [
+    "../media:rtc_audio_video",
+  ]
+}
+
 config("libjingle_peerconnection_warnings_config") {
   # GN orders flags on a target before flags from configs. The default config
   # adds these flags so to cancel them out they need to come from a config and
@@ -85,7 +98,7 @@ config("libjingle_peerconnection_warnings_config") {
   }
 }
 
-rtc_static_library("libjingle_peerconnection") {
+rtc_static_library("peerconnection") {
   cflags = []
   sources = [
     "audiotrack.cc",
@@ -146,19 +159,17 @@ rtc_static_library("libjingle_peerconnection") {
   }
 
   deps = [
-    ":rtc_pc",
+    ":rtc_pc_base",
     "..:webrtc_common",
     "../api:call_api",
     "../api:rtc_stats_api",
-    "../api/audio_codecs:builtin_audio_decoder_factory",
-    "../api/audio_codecs:builtin_audio_encoder_factory",
     "../api/video_codecs:video_codecs_api",
     "../base:rtc_base",
     "../base:rtc_base_approved",
-    "../call",
+    "../call:call_interfaces",
     "../logging:rtc_event_log_api",
-    "../media",
-    "../modules/audio_device:audio_device",
+    "../media:rtc_data",
+    "../media:rtc_media_base_data",
     "../p2p:rtc_p2p",
     "../stats",
     "../system_wrappers:system_wrappers",
@@ -167,6 +178,73 @@ rtc_static_library("libjingle_peerconnection") {
   public_deps = [
     "../api:libjingle_peerconnection_api",
   ]
+}
+
+# This target implements the CreatePeerConnectionFactory methods to build WebRTC
+# with full support(audio, video and datachannel). The applications would be
+# responsible to create their own implementation of CreatePeerConnectionFactory
+# methods with different dependencies based on their requirements.
+# The target "create_pc_factory_datachannelonly" is an example.

[the sun, 2017/06/12 20:58:41]

I'd think create_pc_factory is example enough and the implementation(s) used in
the JNI layer are "application" specific.

[Zhi Huang, 2017/06/12 22:18:58]

Acknowledged.

+rtc_static_library("create_pc_factory") {
+  sources = [
+    "createpeerconnectionfactory.cc",
+  ]
+
+  deps = [
+    "../api:audio_mixer_api",
+    "../api:libjingle_peerconnection_api",
+    "../api/audio_codecs:audio_codecs_api",
+    "../api/audio_codecs:builtin_audio_decoder_factory",
+    "../api/audio_codecs:builtin_audio_encoder_factory",
+    "../base:rtc_base",
+    "../base:rtc_base_approved",
+    "../call",
+    "../call:call_interfaces",
+    "../logging:rtc_event_log_api",
+    "../media:rtc_audio_video",
+    "../modules/audio_device:audio_device",
+  ]
+
+  configs += [ ":libjingle_peerconnection_warnings_config" ]
+
+  if (!build_with_chromium && is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+  }
+}
+
+# This target implements the CreatePeerConnectionFactory methods to build WebRTC
+# with datachannel only support.
+rtc_static_library("create_pc_factory_datachannelonly") {

[the sun, 2017/06/12 20:58:41]

Is it possible to move these variants to the JNI code? IIUC we have "link time
polymorphism" again here. I understand we need it for the Java layer, to support
the different configs, but lets keep it there then.

[Zhi Huang, 2017/06/12 22:18:58]

So you are suggesting to compile this file in the jni target?  I think that
would work if the JNI owner is OK with it.

+  sources = [
+    "createpeerconnectionfactory_datachannelonly.cc",
+  ]
+
+  deps = [
+    "../api:audio_mixer_api",
+    "../api:libjingle_peerconnection_api",
+    "../base:rtc_base",
+    "../base:rtc_base_approved",
+    "../call:call_interfaces",
+    "../logging:rtc_event_log_api",
+  ]
+
+  configs += [ ":libjingle_peerconnection_warnings_config" ]
+
+  if (!build_with_chromium && is_clang) {
+    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
+  }
+}
+
+# TODO(zhihuang): Remove this once the downstream dependencies start using the
+# modular targets.
+rtc_source_set("libjingle_peerconnection") {
+  public_deps = [
+    ":create_pc_factory",
+    ":peerconnection",
+    "../api:libjingle_peerconnection_api",
+  ]
 
   if (rtc_use_quic) {
     sources += [
@@ -244,6 +322,13 @@ if (rtc_include_tests) {
   }
 
   rtc_source_set("pc_test_utils") {
+    # Cannot have GN check enabled because this target would also be used in the
+    # "peerconnection_datachannelonly_unittests" and we don't want to depend on
+    # the target "media:rtc_media_tests_utils" indrectly since it contains all
+    # the audio and video related classes.
+    # TODO(zhihuang): Enable the check once the "media:rtc_media_tests_utils" is
+    # broken down to modular sub-targets.
+    check_includes = false
     testonly = true
     sources = [
       "test/fakeaudiocapturemodule.cc",
@@ -264,15 +349,13 @@ if (rtc_include_tests) {
     ]
 
     deps = [
-      ":libjingle_peerconnection",
+      ":peerconnection",
       "..:webrtc_common",
       "../api:libjingle_peerconnection_test_api",
       "../api:rtc_stats_api",
       "../base:rtc_base",
       "../base:rtc_base_approved",
       "../base:rtc_base_tests_utils",
-      "../media:rtc_media",
-      "../media:rtc_media_tests_utils",
       "../modules/audio_device:audio_device",
       "../p2p:p2p_test_utils",
       "../test:test_support",
@@ -398,4 +481,63 @@ if (rtc_include_tests) {
       shard_timeout = 900
     }
   }
+
+  rtc_test("peerconnection_datachannelonly_unittests") {

[the sun, 2017/06/12 20:58:41]

You shouldn't need a separate target for this - the test could be part of the
default pc test suite. If all link time polymorphism is gone, the compiler will
instead be used to verify how PCF is instantiated (and we could conceivably have
different configurations at once, within the same process).

[Zhi Huang, 2017/06/12 22:18:58]

Acknowledged.

+    check_includes = false  # TODO(zhihuang): Remove (bugs.webrtc.org/6828)
+    testonly = true
+    sources = [
+      "peerconnection_datachannelonly_unittest.cc",
+    ]
+
+    configs += [ ":peerconnection_unittests_config" ]
+
+    if (!build_with_chromium && is_clang) {
+      # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
+      suppressed_configs += [ "//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 = []
+    if (is_android) {
+      sources += [
+        "test/androidtestinitializer.cc",
+        "test/androidtestinitializer.h",
+      ]
+      deps += [
+        "//testing/android/native_test:native_test_support",
+        "//webrtc/sdk/android:base_jni",
+        "//webrtc/sdk/android:libjingle_peerconnection_java",
+        "//webrtc/sdk/android:null_video_jni",
+      ]
+    }
+
+    deps += [
+      ":create_pc_factory_datachannelonly",
+      ":pc_test_utils",
+      ":peerconnection",
+      "..:webrtc_common",
+      "../api:fakemetricsobserver",
+      "../base:rtc_base_approved",
+      "../base:rtc_base_tests_main",
+      "../base:rtc_base_tests_utils",
+      "../modules/utility",
+      "../pc:rtc_pc_base",
+      "../system_wrappers:metrics_default",
+      "//testing/gmock",
+    ]
+
+    if (is_android) {
+      deps += [ "//testing/android/native_test:native_test_support" ]
+      shard_timeout = 900
+    }
+  }
 }