Improve validation when creating audio streams.

BUG=166795
Review URL: https://codereview.chromium.org/11647012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@173981 0039d316-1c4b-4281-b951-d872f2087c98
void AudioInputRendererHost::OnSetVolume(int stream_id, double volume) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

  AudioEntry* entry = LookupById(stream_id);
  if (!entry) {
    SendErrorMessage(stream_id);
    return;
  }

  entry->controller->SetVolume(volume);
}

void AudioInputRendererHost::OnSetVolume(int stream_id, double volume) {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

  AudioEntry* entry = LookupById(stream_id);
  if (!entry) {
    SendErrorMessage(stream_id);
    return;
  }

  entry->controller->SetVolume(volume);
}
