Remove usage of VoEVolumeControl from WVoE and Audio[Send|Receive]Stream.

webrtc/voice_engine/channel_proxy.cc

Index: webrtc/voice_engine/channel_proxy.cc
diff --git a/webrtc/voice_engine/channel_proxy.cc b/webrtc/voice_engine/channel_proxy.cc
index 5538d9ee9e026255c25f2198de2373fe056b3326..ca1d3596c888191dbb4a04b99427080d7220f855 100644
--- a/webrtc/voice_engine/channel_proxy.cc
+++ b/webrtc/voice_engine/channel_proxy.cc
@@ -128,6 +128,14 @@ AudioDecodingCallStats ChannelProxy::GetDecodingCallStatistics() const {
   return stats;
 }
 
+int32_t ChannelProxy::GetSpeechOutputLevel() const {
+  RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
+  uint32_t level = 0;

[kwiberg-webrtc, 2017/02/28 13:59:18]

Why initialize?

[the sun, 2017/03/02 00:36:25]

Variables should always be initialized, unless there is a particular performance
reason why not to. In particular with an interface like the below function, it's
not evident that it may always be set without looking closely at the underlying
code.

[kwiberg-webrtc, 2017/03/02 02:37:37]

On the contrary, I'd argue that the call below is expected to *always* set level
unless it signals an error (this is the usual contract for output parameters).
By not initializing level, you give MemorySanitizer a chance to verify this, and
you tell the reader of the code that you expect level to always be filled in
with a real value.

Initializing to a default value you're sure won't be needed is akin to having a
default case in a switch that you don't think you need. It can hide bugs, and
readers may be fooled into thinking the default value is actually needed.

+  int error = channel()->GetSpeechOutputLevel(level);

[kwiberg-webrtc, 2017/02/28 13:59:18]

const?

[the sun, 2017/03/02 00:36:25]

For error? No.

+  RTC_DCHECK_EQ(0, error);
+  return static_cast<int32_t>(level);
+}
+
 int32_t ChannelProxy::GetSpeechOutputLevelFullRange() const {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   uint32_t level = 0;