Add Android Camera To Unity Plugin

webrtc/examples/unityplugin/unity_plugin_apis.h

Index: webrtc/examples/unityplugin/unity_plugin_apis.h
diff --git a/webrtc/examples/unityplugin/unity_plugin_apis.h b/webrtc/examples/unityplugin/unity_plugin_apis.h
index ee7d709583b83074c788a8800bbc099b2a0a7ca9..529c7d2cc02a904a3fda6b8f85f33a34b187221a 100644
--- a/webrtc/examples/unityplugin/unity_plugin_apis.h
+++ b/webrtc/examples/unityplugin/unity_plugin_apis.h
@@ -37,7 +37,11 @@ typedef void (*AUDIOBUSREADY_CALLBACK)(const void* audio_data,
                                        int number_of_channels,
                                        int number_of_frames);
 
+#if defined(WEBRTC_WIN)
 #define WEBRTC_PLUGIN_API __declspec(dllexport)
+#elif defined(WEBRTC_ANDROID)
+#define WEBRTC_PLUGIN_API __attribute__((visibility("default")))
+#endif
 extern "C" {
 // Create a peerconnection and return a unique peer connection id.
 WEBRTC_PLUGIN_API int CreatePeerConnection(const char** turn_urls,