Set frame length for frame converting in external renderer

ISSUE = Issue 1342
TEST  = Manual Test
Review URL: https://webrtc-codereview.appspot.com/1083005

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3451 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/video_engine/vie_renderer.cc b/video_engine/vie_renderer.cc
index df59f61..2bc7044 100644
--- a/video_engine/vie_renderer.cc
+++ b/video_engine/vie_renderer.cc
@@ -203,7 +203,10 @@
     case kVideoARGB4444:
     case kVideoARGB1555 :
       {
-        ConvertFromI420(video_frame, type, 0, converted_frame_->Buffer());
+        if (ConvertFromI420(video_frame, type, 0,
+                            converted_frame_->Buffer()) < 0)
+          return -1;
+        converted_frame_->SetLength(buffer_size);
       }
       break;
     case kVideoIYUV: