Limit the max volume to 255 before pass it to APM.

content/renderer/media/webrtc_audio_capturer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/webrtc_audio_capturer.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ skipping 442 matching lines @@
   TrackList::ItemList tracks;
   TrackList::ItemList tracks_to_notify_format;
   int current_volume = 0;
   base::TimeDelta audio_delay;
   bool need_audio_processing = true;
   {
     base::AutoLock auto_lock(lock_);
     if (!running_)
       return;
 
-    // Map internal volume range of [0.0, 1.0] into [0, 255] used by the
-    // webrtc::VoiceEngine. webrtc::VoiceEngine will handle the case when the
-    // volume is higher than 255.
+    // Map internal volume range of [0.0, 1.0] into [0, 255] used by AGC.
+    // The volume can be higher than 255 on Linux, and it will be cropped to
+    // 255 since AGC does not allow values out of range.
     volume_ = static_cast<int>((volume * MaxVolume()) + 0.5);
-    current_volume = volume_;
+    current_volume = volume_ > MaxVolume() ? MaxVolume() : volume_;
     audio_delay = base::TimeDelta::FromMilliseconds(audio_delay_milliseconds);
     audio_delay_ = audio_delay;
     key_pressed_ = key_pressed;
     tracks = tracks_.Items();
     tracks_.RetrieveAndClearTags(&tracks_to_notify_format);
 
     // Set the flag to turn on the audio processing in PeerConnection level.
     // Note that, we turn off the audio processing in PeerConnection if the
     // processor has already processed the data.
     need_audio_processing = need_audio_processing_ ?
@@ skipping 127 matching lines @@
   DCHECK_NE(aec_dump_file, base::kInvalidPlatformFileValue);
   audio_processor_->StartAecDump(aec_dump_file);
 }
 
 void WebRtcAudioCapturer::StopAecDump() {
   DCHECK(thread_checker_.CalledOnValidThread());
   audio_processor_->StopAecDump();
 }
 
 }  // namespace content