Revert of Delete VideoFrame default constructor, and IsZeroSize method.

webrtc/media/base/videobroadcaster_unittest.cc

Index: webrtc/media/base/videobroadcaster_unittest.cc
diff --git a/webrtc/media/base/videobroadcaster_unittest.cc b/webrtc/media/base/videobroadcaster_unittest.cc
index c80f0853af336c38851d57da40ec9f47a759af2a..6a8c618bb6a78d1a5059d57b0bbd2c55225342f3 100644
--- a/webrtc/media/base/videobroadcaster_unittest.cc
+++ b/webrtc/media/base/videobroadcaster_unittest.cc
@@ -37,15 +37,8 @@
   FakeVideoRenderer sink2;
   broadcaster.AddOrUpdateSink(&sink1, rtc::VideoSinkWants());
   broadcaster.AddOrUpdateSink(&sink2, rtc::VideoSinkWants());
-  static int kWidth = 100;
-  static int kHeight = 50;
 
-  rtc::scoped_refptr<webrtc::I420Buffer> buffer(
-      webrtc::I420Buffer::Create(kWidth, kHeight));
-  // Initialize, to avoid warnings on use of initialized values.
-  buffer->SetToBlack();
-
-  webrtc::VideoFrame frame(buffer, webrtc::kVideoRotation_0, 0);
+  webrtc::VideoFrame frame;
 
   broadcaster.OnFrame(frame);
   EXPECT_EQ(1, sink1.num_rendered_frames());