Android: Improve handling of RGB texture frames

webrtc/sdk/android/src/java/org/webrtc/TextureBufferImpl.java

Index: webrtc/sdk/android/src/java/org/webrtc/TextureBufferImpl.java
diff --git a/webrtc/sdk/android/src/java/org/webrtc/TextureBufferImpl.java b/webrtc/sdk/android/src/java/org/webrtc/TextureBufferImpl.java
index c2b2010ef2b19b2d373a33012864e4e8f67b6d40..3a7da8d45c366fc87e0bea2862cb1ddf7abfcfe5 100644
--- a/webrtc/sdk/android/src/java/org/webrtc/TextureBufferImpl.java
+++ b/webrtc/sdk/android/src/java/org/webrtc/TextureBufferImpl.java
@@ -67,6 +67,9 @@ class TextureBufferImpl implements VideoFrame.TextureBuffer {
 
   @Override
   public VideoFrame.I420Buffer toI420() {
+    if (type == Type.RGB) {
+      throw new RuntimeException("toI420 for RGB frames not implemented yet");
+    }
     // SurfaceTextureHelper requires a stride that is divisible by 8.  Round width up.
     // See SurfaceTextureHelper for details on the size and format.
     int stride = ((width + 7) / 8) * 8;