Enable libjingle_peerconnection_datachannelonly_so target.

This change also wires up the rest of the production code in
webrtc/sdk/android to be built when the directory is a dependency.

BUG=webrtc:7613
NOTRY=True

Change-Id: Ideda181970a5a570c3f8148b033e471e926243d1
Reviewed-on: https://chromium-review.googlesource.com/548038
Reviewed-by: Zhi Huang <zhihuang@webrtc.org>
Commit-Queue: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18791}
diff --git a/webrtc/sdk/BUILD.gn b/webrtc/sdk/BUILD.gn
index 9526d60..a9fcfb6 100644
--- a/webrtc/sdk/BUILD.gn
+++ b/webrtc/sdk/BUILD.gn
@@ -18,10 +18,14 @@
 }
 
 group("sdk") {
-  if (!build_with_chromium && is_ios) {
-    public_deps = [
-      ":objc_framework",
-    ]
+  public_deps = []
+  if (!build_with_chromium) {
+    if (is_android) {
+      public_deps += [ "android" ]
+    }
+    if (is_ios) {
+      public_deps += [ ":objc_framework" ]
+    }
   }
 }