Renamed FrameObject to EncodedFrame.

The plan is to:
 1. Move FrameObject to api/video.
 2. Rename FrameObject to EncodedFrame.
 3. Move EncodedFrame out of the video_coding namespace.

This is the 2nd CL.

Bug: webrtc:8909
Change-Id: I5e76a0a3b306156b8bc1de67834b4adf14bebef9
Reviewed-on: https://webrtc-review.googlesource.com/56182
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Tommi <tommi@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22158}
diff --git a/modules/video_coding/frame_object.cc b/modules/video_coding/frame_object.cc
index 3bb5283..4aa18ba 100644
--- a/modules/video_coding/frame_object.cc
+++ b/modules/video_coding/frame_object.cc
@@ -32,11 +32,11 @@
   VCMPacket* first_packet = packet_buffer_->GetPacket(first_seq_num);
   RTC_CHECK(first_packet);
 
-  // RtpFrameObject members
+  // EncodedFrame members
   frame_type_ = first_packet->frameType;
   codec_type_ = first_packet->codec;
 
-  // TODO(philipel): Remove when encoded image is replaced by FrameObject.
+  // TODO(philipel): Remove when encoded image is replaced by EncodedFrame.
   // VCMEncodedFrame members
   CopyCodecSpecific(&first_packet->video_header);
   _completeFrame = true;
@@ -68,7 +68,7 @@
   _encodedWidth = first_packet->width;
   _encodedHeight = first_packet->height;
 
-  // FrameObject members
+  // EncodedFrame members
   timestamp = first_packet->timestamp;
 
   VCMPacket* last_packet = packet_buffer_->GetPacket(last_seq_num);