Fix PipelineStatus reporting where video_codec_name is missing.
Fix PipelineStatus reporting where video_codec_name is missing.

The old code used avcodec_find_decoder() to determine the codec
name, which does not work when the decoder is not enabled; e.g.,
h264 on Android.  Instead use codec descriptor fields to get the
codec name, which are always available regardless of decoder
support.  We use this path for populating codec hashes today.

Not sure this fixes the linked bug entirely, but is at least one
fix necessary.

BUG=589717
TEST=none

Review URL: https://codereview.chromium.org/1745663002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#378041}

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