Pass audio to AudioEncoder::Encode() in an ArrayView

Instead of in separate pointer and size arguments.

Review URL: https://codereview.webrtc.org/1418423010

Cr-Commit-Position: refs/heads/master@{#10535}

webrtc/modules/audio_coding/codecs/cng/include/audio_encoder_cng.h

@@ -57,7 +57,7 @@ class AudioEncoderCng final : public AudioEncoder {
   size_t Max10MsFramesInAPacket() const override;
   int GetTargetBitrate() const override;
   EncodedInfo EncodeInternal(uint32_t rtp_timestamp,
-                             const int16_t* audio,
+                             rtc::ArrayView<const int16_t> audio,
                              size_t max_encoded_bytes,
                              uint8_t* encoded) override;
   void Reset() override;