Simplifying audio network adaptor by moving receiver frame length range to ctor.

webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.h

Index: webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.h
diff --git a/webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.h b/webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.h
index 342668e78002976165d3d453256cc321680fb606..f7a364bf7d7893a01e251aea7e55f57f847b313e 100644
--- a/webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.h
+++ b/webrtc/modules/audio_coding/codecs/opus/audio_encoder_opus.h
@@ -49,6 +49,7 @@ class AudioEncoderOpus final : public AudioEncoder {
     int max_playback_rate_hz = 48000;
     int complexity = kDefaultComplexity;
     bool dtx_enabled = false;
+    std::vector<int> supported_frame_lengths_ms;
     const Clock* clock = nullptr;
 
    private:
@@ -102,6 +103,9 @@ class AudioEncoderOpus final : public AudioEncoder {
   void OnReceivedRtt(int rtt_ms) override;
   void SetReceiverFrameLengthRange(int min_frame_length_ms,
                                    int max_frame_length_ms) override;
+  const std::vector<int>& supported_frame_lengths_ms() const {

[kwiberg-webrtc, 2016/10/19 09:12:01]

Again, I wonder if the return type here shouldn't be rtc::ArrayView<const int>.

[minyue-webrtc, 2016/10/19 09:25:54]

if config_.supported_frame_lengths_ms is a vector, it is any benefit of
returning rtc::ArrayView<const int>

[kwiberg-webrtc, 2016/10/19 10:43:33]

No, but there are also no disadvantages. And the API then makes it possible for
you to change how you store the supported frame lengths.

Basically, everywhere where you pass an array of contiguous elements as a
function argument or return value, and the recipient is only allowed to access
the elements and not do anything to the length or ownership of the array,
rtc::ArrayView is just as good as std::vector&, rtc::Buffer&, etc., but places
fewer restrictions on how that memory is managed.

[minyue-webrtc, 2016/10/21 08:26:29]

ok, yes, changed to rtc::ArrayView. Thanks for the explanation, This will also
help in my future CLs.

+    return config_.supported_frame_lengths_ms;
+  }
 
   // Getters for testing.
   double packet_loss_rate() const { return packet_loss_rate_; }