message: Delete unused class DummyDtmfObserver
  There's another copy in peer_connection_integrationtest.cc, which is
  used by one test.
  Cr-Commit-Position: refs/heads/master@{#33480}
diff: @@ -83,26 +83,6 @@ class DataChannelIntegrationTestUnifiedPlan
  : PeerConnectionIntegrationBaseTest(SdpSemantics::kUnifiedPlan) {}
  };
  -class DummyDtmfObserver : public DtmfSenderObserverInterface {
  - public:
  - DummyDtmfObserver() : completed_(false) {}
  -
  - // Implements DtmfSenderObserverInterface.
  - void OnToneChange(const std::string& tone) override {
  - tones_.push_back(tone);
  - if (tone.empty()) {
  - completed_ = true;
  - }
  - }
  -
  - const std::vector<std::string>& tones() const { return tones_; }
  - bool completed() const { return completed_; }
  -
  - private:
  - bool completed_;
  - std::vector<std::string> tones_;
  -};
  -
  #ifdef WEBRTC_HAVE_SCTP
  // This test causes a PeerConnection to enter Disconnected state, and
  