media/gpu/v4l2VEA: NotifyError() with kPlatformFailure if unexpected VideoFrame is fed on Encode()

V4L2VEA doesn't allow change coded_size of VideoFrame during
encoding. If the size varies, it invokes NotifyError() with
kInvalidArgumentError. However, RtcVideoEncoder does not regard
the error as so critical that software encoder fallback should be
triggered. As a result, any frame will no longer be encoded if it
happens, which is viewed like encoding hangs.

This CL lets V4L2VEA invoke NotifyError() with KPlatformFailure
in the case so that software encoder fallback happens.

Bug: 1057528
Test: SW encoder fallback happens upon rotation on scarlet
Change-Id: I8300e42d3a913548736e9d17bba6d394f12345cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2087329
Commit-Queue: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Alexandre Courbot <acourbot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748526}

media/gpu/v4l2/v4l2_video_encode_accelerator.cc

@@ -692,7 +692,7 @@ void V4L2VideoEncodeAccelerator::EncodeTask(scoped_refptr<VideoFrame> frame,
   }
 
   if (frame && !ReconfigureFormatIfNeeded(*frame)) {
-    NOTIFY_ERROR(kInvalidArgumentError);
+    NOTIFY_ERROR(kPlatformFailureError);
     encoder_state_ = kError;
     return;
   }
@@ -722,6 +722,7 @@ bool V4L2VideoEncodeAccelerator::ReconfigureFormatIfNeeded(
   }
 
   if (!input_buffer_map_.empty()) {
+    // TODO(crbug.com/1060057): Handle coded_size change.
     if (frame.coded_size() != input_frame_size_) {
       VLOGF(1) << "Input frame size is changed during encoding"
                << ", frame.coded_size()=" << frame.coded_size().ToString()