Add Alpha Channel Support For WebRTC Unity Plugin

This CL make webrtc unity plugin compatible with alpha channel support.

Bug: webrtc:8645
Change-Id: I3250aede47b31c4685e57d11fb2b2e86b824f9c4
Reviewed-on: https://webrtc-review.googlesource.com/32325
Commit-Queue: Qiang Chen <qiangchen@chromium.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: George Zhou <gyzhou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#21394}
diff --git a/examples/unityplugin/unity_plugin_apis.cc b/examples/unityplugin/unity_plugin_apis.cc
index ae98a83..34c28d9 100644
--- a/examples/unityplugin/unity_plugin_apis.cc
+++ b/examples/unityplugin/unity_plugin_apis.cc
@@ -24,12 +24,13 @@
 int CreatePeerConnection(const char** turn_urls,
                          const int no_of_urls,
                          const char* username,
-                         const char* credential) {
+                         const char* credential,
+                         bool mandatory_receive_video) {
   g_peer_connection_map[g_peer_connection_id] =
       new rtc::RefCountedObject<SimplePeerConnection>();
 
   if (!g_peer_connection_map[g_peer_connection_id]->InitializePeerConnection(
-          turn_urls, no_of_urls, username, credential, false))
+          turn_urls, no_of_urls, username, credential, mandatory_receive_video))
     return -1;
 
   return g_peer_connection_id++;