expose webrtc version for android (#6)

Author: kanat

sdk/android/BUILD.gn

@@ -156,6 +156,8 @@ if (is_android) {
     sources = [
       "api/org/webrtc/Predicate.java",
       "api/org/webrtc/RefCounted.java",
+      "api/org/webrtc/WebrtcBuildVersion.java",
+      "src/java/org/webrtc/ApplicationContextProvider.java",
       "src/java/org/webrtc/CalledByNative.java",
       "src/java/org/webrtc/CalledByNativeUnchecked.java",
       "src/java/org/webrtc/Histogram.java",