Rename I420VideoFrame to VideoFrame.

This is a mechanical change since it affects so many
files.
I420VideoFrame -> VideoFrame
and reformatted.

Rationale: in the next CL I420VideoFrame will
get an indication of Pixel Format (I420 for
starters) and of storage type: usually
UNOWNED, could be SHMEM, and in the near
future will be possibly TEXTURE. See
https://codereview.chromium.org/1154153003
for the change that happened in Cr.

BUG=4730, chromium:440843
R=jiayl@webrtc.org, niklas.enbom@webrtc.org, pthatcher@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/52629004

Cr-Commit-Position: refs/heads/master@{#9339}
diff --git a/webrtc/test/fake_encoder.cc b/webrtc/test/fake_encoder.cc
index 4c8d768..3a80b98 100644
--- a/webrtc/test/fake_encoder.cc
+++ b/webrtc/test/fake_encoder.cc
@@ -45,10 +45,9 @@
   return 0;
 }
 
-int32_t FakeEncoder::Encode(
-    const I420VideoFrame& input_image,
-    const CodecSpecificInfo* codec_specific_info,
-    const std::vector<VideoFrameType>* frame_types) {
+int32_t FakeEncoder::Encode(const VideoFrame& input_image,
+                            const CodecSpecificInfo* codec_specific_info,
+                            const std::vector<VideoFrameType>* frame_types) {
   assert(config_.maxFramerate > 0);
   int64_t time_since_last_encode_ms = 1000 / config_.maxFramerate;
   int64_t time_now_ms = clock_->TimeInMilliseconds();
@@ -188,7 +187,7 @@
     : test::FakeEncoder(clock),
       delay_ms_(delay_ms) {}
 
-int32_t DelayedEncoder::Encode(const I420VideoFrame& input_image,
+int32_t DelayedEncoder::Encode(const VideoFrame& input_image,
                                const CodecSpecificInfo* codec_specific_info,
                                const std::vector<VideoFrameType>* frame_types) {
   SleepMs(delay_ms_);