Refactor RMSLevel and give it new functionality

webrtc/modules/audio_processing/level_estimator_impl.cc

Index: webrtc/modules/audio_processing/level_estimator_impl.cc
diff --git a/webrtc/modules/audio_processing/level_estimator_impl.cc b/webrtc/modules/audio_processing/level_estimator_impl.cc
index 187873e33e00f2e20bb3745045eedb06c322e3eb..a1b3da611064f7fd913984025fc16ed3ef5fd8c5 100644
--- a/webrtc/modules/audio_processing/level_estimator_impl.cc
+++ b/webrtc/modules/audio_processing/level_estimator_impl.cc
@@ -36,7 +36,8 @@ void LevelEstimatorImpl::ProcessStream(AudioBuffer* audio) {
   }
 
   for (size_t i = 0; i < audio->num_channels(); i++) {
-    rms_->Process(audio->channels_const()[i], audio->num_frames());
+    rms_->Process(rtc::ArrayView<const int16_t>(audio->channels_const()[i],
+                                                audio->num_frames()));
   }
 }