GN Templates: Introduce rtc_shared_library

webrtc/build/webrtc.gni

Index: webrtc/build/webrtc.gni
diff --git a/webrtc/build/webrtc.gni b/webrtc/build/webrtc.gni
index eabdeb20e6c52dcc2c17a7768a1fea71f4bc05cb..01670748b4f00417e050bbe995fcc84f322448cb 100644
--- a/webrtc/build/webrtc.gni
+++ b/webrtc/build/webrtc.gni
@@ -205,6 +205,11 @@ set_defaults("rtc_static_library") {
   suppressed_configs = []
 }
 
+set_defaults("rtc_shared_library") {
+  configs = rtc_add_configs
+  suppressed_configs = []
+}
+
 template("rtc_test") {
   test(target_name) {
     forward_variables_from(invoker,
@@ -285,3 +290,22 @@ template("rtc_static_library") {
     }
   }
 }
+
+template("rtc_shared_library") {
+  shared_library(target_name) {
+    forward_variables_from(invoker,
+                           "*",
+                           [
+                             "configs",
+                             "public_configs",
+                             "suppressed_configs",
+                           ])
+    configs += invoker.configs
+    configs -= rtc_remove_configs
+    configs -= invoker.suppressed_configs
+    public_configs = [ rtc_common_inherited_config ]
+    if (defined(invoker.public_configs)) {
+      public_configs += invoker.public_configs
+    }
+  }
+}