Linux – Google Chrome on Linux not using ALSA for sound

On my laptop, I've got an .asoundrc file that outputs sound to my USB headset. This works fine for SMplayer and Firefox. However, Google Chrome (at least, Flash-based and HTML5-based videos and HTML5-based audio in Chrome) plays through the laptop speakers instead. I've tried running Chrome from a command-line, hoping there would be some helpful output, but no such luck. I've tried looking through Google for whether Chrome even uses ALSA, or if it uses something else, but I have been unsuccessful in this.

This question seems to be the same issue, but no suggestion was made.

Anyone have any ideas? I'm running Gentoo with a 3.10.17 kernel, 1.0.27 ALSA utils, 2.6.5 FVWM, and 36.0.1985.143 Chrome. If you need more info, please let me know.

EDIT:

I've configured the USB headset as the default ALSA device. Volume levels for both headset and onboard are set and un-muted using alsamixer. My .asoundrc file is as follows.

ctl.!default {
  type hw
  card Headset
}

pcm.dmixer {
  type dmix
  ipc_key 1024
  slave {
    pcm {
      type hw
      card Headset
    }
    period_size 1024
    buffer_size 4096
  }
  bindings {
    0 0
    1 1
  }
}

pcm.!default {
  type plug
  slave.pcm dmixer
}

EDIT 2: More info

Ran both mplayer and google-chrome-stable from command-line. Once mplayer was playing a video (and audio), I started Chrome, went to YouTube, and played a video. The audio came out the speakers. Command-line output was as follows:

[27649:27688:0820/162104:ERROR:gservices_settings.cc(103)] Setting not found: checkin_interval
[27649:27748:0820/162105:ERROR:get_updates_processor.cc(240)] PostClientToServerMessage() failed during GetUpdates
[27649:27688:0820/162211:ERROR:raw_channel_posix.cc(139)] recvmsg: Connection reset by peer
[27649:27688:0820/162211:ERROR:channel.cc(297)] RawChannel fatal error (type 1)
[27649:27688:0820/162212:ERROR:raw_channel_posix.cc(139)] recvmsg: Connection reset by peer
[27649:27688:0820/162212:ERROR:channel.cc(297)] RawChannel fatal error (type 1)
[WARNING:flash/platform/pepper/pep_module.cpp(63)] SANDBOXED
[27649:27688:0820/162235:ERROR:raw_channel_posix.cc(139)] recvmsg: Connection reset by peer
[27649:27688:0820/162235:ERROR:channel.cc(297)] RawChannel fatal error (type 1)