Protect AudioRendererAlgorithm from invalid step sizes.

BUG=165430
TEST=unittests and asan pass.

Review URL: https://codereview.chromium.org/11573023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@173249 0039d316-1c4b-4281-b951-d872f2087c98
void AudioRendererAlgorithm::SetPlaybackRate(float new_rate) {
  DCHECK_GE(new_rate, 0.0);
  playback_rate_ = new_rate;
  muted_ =
      playback_rate_ < kMinPlaybackRate || playback_rate_ > kMaxPlaybackRate;

  ResetWindow();
}

void AudioRendererAlgorithm::SetPlaybackRate(float new_rate) {
  DCHECK_GE(new_rate, 0.0);
  playback_rate_ = new_rate;
  muted_ =
      playback_rate_ < kMinPlaybackRate || playback_rate_ > kMaxPlaybackRate;

  ResetWindow();
}
