Clean out unused methods from VoiceEngine and VoEBase.

voice_engine/voice_engine_fixture.cc

Index: voice_engine/voice_engine_fixture.cc
diff --git a/voice_engine/voice_engine_fixture.cc b/voice_engine/voice_engine_fixture.cc
index eb605c9c5b3b761626e342bdddc6b28a36ab8963..c167b40135ec7067b89b359e7c75c86065171fc8 100644
--- a/voice_engine/voice_engine_fixture.cc
+++ b/voice_engine/voice_engine_fixture.cc
@@ -19,13 +19,11 @@ VoiceEngineFixture::VoiceEngineFixture()
       network_(VoENetwork::GetInterface(voe_)) {
   EXPECT_NE(nullptr, base_);
   EXPECT_NE(nullptr, network_);
-  EXPECT_EQ(0, base_->RegisterVoiceEngineObserver(observer_));
   apm_ = new rtc::RefCountedObject<test::MockAudioProcessing>();
 }
 
 VoiceEngineFixture::~VoiceEngineFixture() {
   EXPECT_EQ(2, network_->Release());
-  EXPECT_EQ(0, base_->DeRegisterVoiceEngineObserver());
   EXPECT_EQ(0, base_->Terminate());
   EXPECT_EQ(1, base_->Release());
   EXPECT_TRUE(VoiceEngine::Delete(voe_));