Build WebRTC with data channel only.

webrtc/media/BUILD.gn

 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/linux/pkg_config.gni")
 import("../webrtc.gni")
@@ skipping 14 matching lines @@
 
 config("rtc_media_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
   # cannot be on the target directly.
   if (!is_win) {
     cflags = [ "-Wno-deprecated-declarations" ]
   }
 }
 
-rtc_static_library("rtc_media_base") {
+rtc_static_library("rtc_media_base_datachannel_only") {
   # TODO(kjellander): Remove (bugs.webrtc.org/6828)
   # Enabling GN check triggers cyclic dependency error:
   #   //webrtc/media:rtc_media_base ->
   #   //webrtc/pc:rtc_pc ->
   #   //webrtc/media:media ->
   #   //webrtc/media:rtc_media_base
   check_includes = false
   defines = []
   libs = []
   deps = []
@@ skipping 46 matching lines @@
       "$rtc_libyuv_dir",
     ]
   } else {
     # Need to add a directory normally exported by libyuv.
     include_dirs += [ "$rtc_libyuv_dir/include" ]
   }
 
   deps += [
     "..:webrtc_common",
     "../api:libjingle_peerconnection_api",
+    "../api/audio_codecs:audio_codecs_api",
+    "../base:rtc_base",
+    "../base:rtc_base_approved",
+    "../call:call_interfaces",
+    "../p2p",
+  ]
+
+  if (is_nacl) {
+    deps += [ "//native_client_sdk/src/libraries/nacl_io" ]
+  }
+}
+
+rtc_static_library("rtc_media_base") {

[kjellander_webrtc, 2017/05/10 14:20:37]

Can we avoid the duplication here and split out the common parts into smaller
targets (rtc_source_set) ?

[Zhi Huang, 2017/05/10 21:00:35]

Yeah, I can do it here but I need "check_includes = false".

There are some similar cases in other places. I didn't extract the common part
for libjingle_peerconnection_jni target because there are not too many
duplicated files and I'm not sure if it is a good idea to disable the include
check there as well.

+  # TODO(kjellander): Remove (bugs.webrtc.org/6828)
+  # Enabling GN check triggers cyclic dependency error:
+  #   //webrtc/media:rtc_media_base ->
+  #   //webrtc/pc:rtc_pc ->
+  #   //webrtc/media:media ->
+  #   //webrtc/media:rtc_media_base
+  check_includes = false
+  defines = [
+    "HAVE_WEBRTC_VOICE",
+    "HAVE_WEBRTC_VIDEO",
+  ]
+  libs = []
+  deps = []
+  sources = [
+    "base/adaptedvideotracksource.cc",

[kjellander_webrtc, 2017/05/10 14:20:37]

I thought duplicating the same sources in multiple targets like this was a build
error or at least warning, but it doesn't seem to be the case. I guess it's
because the rtc_media_base_datachannel_only target is not built by default,
since it doesn't seem to be a part of the dependency chain down from the
//:default target in
https://chromium.googlesource.com/external/webrtc/+/master/BUILD.gn

This is a fortunate side-effect of the work I did in
https://bugs.chromium.org/p/webrtc/issues/detail?id=6440 but it also makes these
targets actually be built if you specify their names explicitly on the command
line (if you specify nothing, only  //:default is built)

[Zhi Huang, 2017/05/10 21:00:35]

Yes, this is very fortunate. 

But we probably want the _datachannel_only targets and tests to be built on the
trybots so that they won't be accidentally broken.

Then the question is how can we avoid building same file in different targets
since we need to build those files with #ifdef using different "defines" sets to
get different behavior.

+    "base/adaptedvideotracksource.h",
+    "base/audiosource.h",
+    "base/codec.cc",
+    "base/codec.h",
+    "base/cryptoparams.h",
+    "base/device.h",
+    "base/mediachannel.h",
+    "base/mediaconstants.cc",
+    "base/mediaconstants.h",
+    "base/mediaengine.cc",
+    "base/mediaengine.h",
+    "base/rtpdataengine.cc",
+    "base/rtpdataengine.h",
+    "base/rtputils.cc",
+    "base/rtputils.h",
+    "base/streamparams.cc",
+    "base/streamparams.h",
+    "base/turnutils.cc",
+    "base/turnutils.h",
+    "base/videoadapter.cc",
+    "base/videoadapter.h",
+    "base/videobroadcaster.cc",
+    "base/videobroadcaster.h",
+    "base/videocapturer.cc",
+    "base/videocapturer.h",
+    "base/videocapturerfactory.h",
+    "base/videocommon.cc",
+    "base/videocommon.h",
+    "base/videoframe.h",
+    "base/videosourcebase.cc",
+    "base/videosourcebase.h",
+  ]
+
+  configs += [ ":rtc_media_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" ]
+  }
+
+  include_dirs = []
+  if (rtc_build_libyuv) {
+    deps += [ "$rtc_libyuv_dir" ]
+    public_deps = [
+      "$rtc_libyuv_dir",
+    ]
+  } else {
+    # Need to add a directory normally exported by libyuv.
+    include_dirs += [ "$rtc_libyuv_dir/include" ]
+  }
+
+  deps += [
+    "..:webrtc_common",
+    "../api:libjingle_peerconnection_api",
     "../api:video_frame_api",
     "../api/audio_codecs:audio_codecs_api",
     "../api/audio_codecs:builtin_audio_encoder_factory",
     "../base:rtc_base",
     "../base:rtc_base_approved",
     "../call:call_interfaces",
     "../common_video:common_video",
     "../p2p",
   ]
 
   if (is_nacl) {
     deps += [ "//native_client_sdk/src/libraries/nacl_io" ]
   }
 }
 
+rtc_static_library("rtc_media_datachannel_only") {
+  # TODO(kjellander): Remove (bugs.webrtc.org/6828)
+  # Enabling GN check triggers cyclic dependency error:
+  #   //webrtc/media:media ->
+  #   //webrtc/media:rtc_media ->
+  #   //webrtc/pc:rtc_pc ->
+  #   //webrtc/media:media
+  check_includes = false
+  defines = []
+  deps = []
+  sources = [
+    "sctp/sctptransport.cc",
+    "sctp/sctptransport.h",
+    "sctp/sctptransportinternal.h",
+  ]
+
+  configs += [ ":rtc_media_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" ]
+  }
+
+  if (is_win) {
+    cflags = [
+      "/wd4245",  # conversion from "int" to "size_t", signed/unsigned mismatch.
+      "/wd4267",  # conversion from "size_t" to "int", possible loss of data.
+      "/wd4389",  # signed/unsigned mismatch.
+    ]
+  }
+
+  if (rtc_enable_sctp && rtc_build_usrsctp) {
+    include_dirs = [
+      # TODO(jiayl): move this into the public_configs of
+      # //third_party/usrsctp/BUILD.gn.
+      "//third_party/usrsctp/usrsctplib",
+    ]
+    deps += [ "//third_party/usrsctp" ]
+  }
+
+  deps += [
+    ":rtc_media_base_datachannel_only",
+    "..:webrtc_common",
+    "../api:call_api",
+    "../api:transport_api",
+    "../base:rtc_base",
+    "../base:rtc_base_approved",
+    "../p2p:rtc_p2p",
+    "../system_wrappers",
+  ]
+}
+
 rtc_static_library("rtc_media") {
   # TODO(kjellander): Remove (bugs.webrtc.org/6828)
   # Enabling GN check triggers cyclic dependency error:
   #   //webrtc/media:media ->
   #   //webrtc/media:rtc_media ->
   #   //webrtc/pc:rtc_pc ->
   #   //webrtc/media:media
   check_includes = false
   defines = []
   libs = []
@@ skipping 333 matching lines @@
       "../modules/video_coding:video_coding_utility",
       "../modules/video_coding:webrtc_vp8",
       "../p2p:p2p_test_utils",
       "../system_wrappers:metrics_default",
       "../test:audio_codec_mocks",
       "../test:test_support",
       "../voice_engine:voice_engine",
     ]
   }
 }