Revert of MediaStream audio object graph untangling and clean-ups.

content/renderer/media/media_stream_audio_level_calculator.cc

Index: content/renderer/media/media_stream_audio_level_calculator.cc
diff --git a/content/renderer/media/media_stream_audio_level_calculator.cc b/content/renderer/media/media_stream_audio_level_calculator.cc
index 936dcf25c1fb1a66748d6b8e26b68dcf9639ea95..ad76a43dd2f6ad14125b5a92506990e1bbc34aaf 100644
--- a/content/renderer/media/media_stream_audio_level_calculator.cc
+++ b/content/renderer/media/media_stream_audio_level_calculator.cc
@@ -5,7 +5,6 @@
 #include "content/renderer/media/media_stream_audio_level_calculator.h"
 
 #include <cmath>
-#include <limits>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ -29,36 +28,23 @@
 
 }  // namespace
 
-MediaStreamAudioLevelCalculator::Level::Level() : level_(0.0f) {}
-
-MediaStreamAudioLevelCalculator::Level::~Level() {}
-
-float MediaStreamAudioLevelCalculator::Level::GetCurrent() const {
-  base::AutoLock auto_lock(lock_);
-  return level_;
+MediaStreamAudioLevelCalculator::MediaStreamAudioLevelCalculator()
+    : counter_(0),
+      max_amplitude_(0.0f),
+      level_(0.0f) {
 }
 
-void MediaStreamAudioLevelCalculator::Level::Set(float level) {
-  base::AutoLock auto_lock(lock_);
-  level_ = level;
+MediaStreamAudioLevelCalculator::~MediaStreamAudioLevelCalculator() {
 }
 
-MediaStreamAudioLevelCalculator::MediaStreamAudioLevelCalculator()
-    : counter_(0), max_amplitude_(0.0f), level_(new Level()) {}
-
-MediaStreamAudioLevelCalculator::~MediaStreamAudioLevelCalculator() {
-  level_->Set(0.0f);
-}
-
-void MediaStreamAudioLevelCalculator::Calculate(
-    const media::AudioBus& audio_bus,
-    bool assume_nonzero_energy) {
+float MediaStreamAudioLevelCalculator::Calculate(
+    const media::AudioBus& audio_bus) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   // |level_| is updated every 10 callbacks. For the case where callback comes
   // every 10ms, |level_| will be updated approximately every 100ms.
   static const int kUpdateFrequency = 10;
 
-  float max =
-      assume_nonzero_energy ? 1.0f / std::numeric_limits<int16_t>::max() : 0.0f;
+  float max = 0.0f;
   for (int i = 0; i < audio_bus.channels(); ++i) {
     const float max_this_channel =
         MaxAmplitude(audio_bus.channel(i), audio_bus.frames());
@@ -68,8 +54,7 @@
   max_amplitude_ = std::max(max_amplitude_, max);
 
   if (counter_++ == kUpdateFrequency) {
-    // Clip the exposed signal level to make sure it is in the range [0.0,1.0].
-    level_->Set(std::min(1.0f, max_amplitude_));
+    level_ = max_amplitude_;
 
     // Decay the absolute maximum amplitude by 1/4.
     max_amplitude_ /= 4.0f;
@@ -77,6 +62,8 @@
     // Reset the counter.
     counter_ = 0;
   }
+
+  return level_;
 }
 
 }  // namespace content