Use source_sets in component builds and static_library in release builds.

Static libraries don't guarantee that an exported symbol gets linked
into a shared library (and in order to support Chromium's component
build mode, WebRTC needs to be linked as a shared library).

Source sets always pass all the object files to the linker.

On the flip side, source_sets link more object files in release builds
and to avoid this, this CL introduces a the GN template "rtc_library" that
expands to static_library during release builds and to source_set during
component builds.

See: https://gn.googlesource.com/gn/+/master/docs/reference.md#func_source_set

Bug: webrtc:9419
Change-Id: I4667e820c2b3fcec417becbd2034acc13e4f04fe
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157168
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#29525}

api/audio_codecs/BUILD.gn

@@ -12,7 +12,7 @@ if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-rtc_source_set("audio_codecs_api") {
+rtc_library("audio_codecs_api") {
   visibility = [ "*" ]
   sources = [
     "audio_codec_pair_id.cc",
@@ -43,7 +43,7 @@ rtc_source_set("audio_codecs_api") {
   ]
 }
 
-rtc_static_library("builtin_audio_decoder_factory") {
+rtc_library("builtin_audio_decoder_factory") {
   visibility = [ "*" ]
   allow_poison = [ "audio_codecs" ]
   sources = [
@@ -77,7 +77,7 @@ rtc_static_library("builtin_audio_decoder_factory") {
   }
 }
 
-rtc_static_library("builtin_audio_encoder_factory") {
+rtc_library("builtin_audio_encoder_factory") {
   visibility = [ "*" ]
   allow_poison = [ "audio_codecs" ]
   sources = [

api/audio_codecs/L16/BUILD.gn

@@ -12,7 +12,7 @@ if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-rtc_static_library("audio_encoder_L16") {
+rtc_library("audio_encoder_L16") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -30,7 +30,7 @@ rtc_static_library("audio_encoder_L16") {
   ]
 }
 
-rtc_static_library("audio_decoder_L16") {
+rtc_library("audio_decoder_L16") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [

api/audio_codecs/g711/BUILD.gn

@@ -12,7 +12,7 @@ if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-rtc_static_library("audio_encoder_g711") {
+rtc_library("audio_encoder_g711") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -30,7 +30,7 @@ rtc_static_library("audio_encoder_g711") {
   ]
 }
 
-rtc_static_library("audio_decoder_g711") {
+rtc_library("audio_decoder_g711") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [

api/audio_codecs/g722/BUILD.gn

@@ -19,7 +19,7 @@ rtc_source_set("audio_encoder_g722_config") {
   ]
 }
 
-rtc_static_library("audio_encoder_g722") {
+rtc_library("audio_encoder_g722") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -38,7 +38,7 @@ rtc_static_library("audio_encoder_g722") {
   ]
 }
 
-rtc_static_library("audio_decoder_g722") {
+rtc_library("audio_decoder_g722") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [

api/audio_codecs/ilbc/BUILD.gn

@@ -19,7 +19,7 @@ rtc_source_set("audio_encoder_ilbc_config") {
   ]
 }
 
-rtc_static_library("audio_encoder_ilbc") {
+rtc_library("audio_encoder_ilbc") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -37,7 +37,7 @@ rtc_static_library("audio_encoder_ilbc") {
   ]
 }
 
-rtc_static_library("audio_decoder_ilbc") {
+rtc_library("audio_decoder_ilbc") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [

api/audio_codecs/isac/BUILD.gn

@@ -68,7 +68,7 @@ config("isac_config") {
   }
 }
 
-rtc_static_library("audio_encoder_isac_fix") {
+rtc_library("audio_encoder_isac_fix") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -84,7 +84,7 @@ rtc_static_library("audio_encoder_isac_fix") {
   ]
 }
 
-rtc_static_library("audio_decoder_isac_fix") {
+rtc_library("audio_decoder_isac_fix") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -100,7 +100,7 @@ rtc_static_library("audio_decoder_isac_fix") {
   ]
 }
 
-rtc_static_library("audio_encoder_isac_float") {
+rtc_library("audio_encoder_isac_float") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -117,7 +117,7 @@ rtc_static_library("audio_encoder_isac_float") {
   ]
 }
 
-rtc_static_library("audio_decoder_isac_float") {
+rtc_library("audio_decoder_isac_float") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [

api/audio_codecs/opus/BUILD.gn

@@ -12,7 +12,7 @@ if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-rtc_static_library("audio_encoder_opus_config") {
+rtc_library("audio_encoder_opus_config") {
   visibility = [ "*" ]
   sources = [
     "audio_encoder_multi_channel_opus_config.cc",
@@ -40,7 +40,7 @@ rtc_source_set("audio_decoder_opus_config") {
   ]
 }
 
-rtc_source_set("audio_encoder_opus") {
+rtc_library("audio_encoder_opus") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   public = [
@@ -60,7 +60,7 @@ rtc_source_set("audio_encoder_opus") {
   ]
 }
 
-rtc_static_library("audio_decoder_opus") {
+rtc_library("audio_decoder_opus") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [
@@ -77,7 +77,7 @@ rtc_static_library("audio_decoder_opus") {
   ]
 }
 
-rtc_source_set("audio_encoder_multiopus") {
+rtc_library("audio_encoder_multiopus") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   public = [
@@ -96,7 +96,7 @@ rtc_source_set("audio_encoder_multiopus") {
   ]
 }
 
-rtc_static_library("audio_decoder_multiopus") {
+rtc_library("audio_decoder_multiopus") {
   visibility = [ "*" ]
   poisonous = [ "audio_codecs" ]
   sources = [

api/audio_codecs/test/BUILD.gn

@@ -13,7 +13,7 @@ if (is_android) {
 }
 
 if (rtc_include_tests) {
-  rtc_source_set("audio_codecs_api_unittests") {
+  rtc_library("audio_codecs_api_unittests") {
     testonly = true
     sources = [
       "audio_decoder_factory_template_unittest.cc",