Reland of Delete VideoFrame default constructor, and IsZeroSize method.

webrtc/video/vie_encoder.cc

Index: webrtc/video/vie_encoder.cc
diff --git a/webrtc/video/vie_encoder.cc b/webrtc/video/vie_encoder.cc
index b0f01184cefaee5f790a68befd1aee2368e2076e..dc85d29ab20bc9b09c23e05ecf6800f6e775ba69 100644
--- a/webrtc/video/vie_encoder.cc
+++ b/webrtc/video/vie_encoder.cc
@@ -86,10 +86,10 @@ class ViEEncoder::EncodeTask : public rtc::QueuedTask {
              ViEEncoder* vie_encoder,
              int64_t time_when_posted_in_ms,
              bool log_stats)
-      : vie_encoder_(vie_encoder),
+      : frame_(frame),
+        vie_encoder_(vie_encoder),
         time_when_posted_ms_(time_when_posted_in_ms),
         log_stats_(log_stats) {
-    frame_ = frame;
     ++vie_encoder_->posted_frames_waiting_for_encode_;
   }