Replace NULL with nullptr in all C++ files.

webrtc/voice_engine/voe_external_media_impl.cc

Index: webrtc/voice_engine/voe_external_media_impl.cc
diff --git a/webrtc/voice_engine/voe_external_media_impl.cc b/webrtc/voice_engine/voe_external_media_impl.cc
index 85305c82243242e35bf35b42ae988b7a4e8d9dbc..7f76b0a5c5a106dd188a198661e395f89d9227d2 100644
--- a/webrtc/voice_engine/voe_external_media_impl.cc
+++ b/webrtc/voice_engine/voe_external_media_impl.cc
@@ -21,8 +21,8 @@
 namespace webrtc {
 
 VoEExternalMedia* VoEExternalMedia::GetInterface(VoiceEngine* voiceEngine) {
-  if (NULL == voiceEngine) {
-    return NULL;
+  if (nullptr == voiceEngine) {
+    return nullptr;
   }
   VoiceEngineImpl* s = static_cast<VoiceEngineImpl*>(voiceEngine);
   s->AddRef();
@@ -61,7 +61,7 @@ int VoEExternalMediaImpl::RegisterExternalMediaProcessing(
     case kRecordingPerChannel: {
       voe::ChannelOwner ch = shared_->channel_manager().GetChannel(channel);
       voe::Channel* channelPtr = ch.channel();
-      if (channelPtr == NULL) {
+      if (channelPtr == nullptr) {
         shared_->SetLastError(
             VE_CHANNEL_NOT_VALID, kTraceError,
             "RegisterExternalMediaProcessing() failed to locate "
@@ -97,7 +97,7 @@ int VoEExternalMediaImpl::DeRegisterExternalMediaProcessing(
     case kRecordingPerChannel: {
       voe::ChannelOwner ch = shared_->channel_manager().GetChannel(channel);
       voe::Channel* channelPtr = ch.channel();
-      if (channelPtr == NULL) {
+      if (channelPtr == nullptr) {
         shared_->SetLastError(VE_CHANNEL_NOT_VALID, kTraceError,
                               "RegisterExternalMediaProcessing() "
                               "failed to locate channel");
@@ -124,7 +124,7 @@ int VoEExternalMediaImpl::GetAudioFrame(int channel, int desired_sample_rate_hz,
   }
   voe::ChannelOwner ch = shared_->channel_manager().GetChannel(channel);
   voe::Channel* channelPtr = ch.channel();
-  if (channelPtr == NULL) {
+  if (channelPtr == nullptr) {
     shared_->SetLastError(VE_CHANNEL_NOT_VALID, kTraceError,
                           "GetAudioFrame() failed to locate channel");
     return -1;
@@ -165,7 +165,7 @@ int VoEExternalMediaImpl::SetExternalMixing(int channel, bool enable) {
   }
   voe::ChannelOwner ch = shared_->channel_manager().GetChannel(channel);
   voe::Channel* channelPtr = ch.channel();
-  if (channelPtr == NULL) {
+  if (channelPtr == nullptr) {
     shared_->SetLastError(VE_CHANNEL_NOT_VALID, kTraceError,
                           "SetExternalMixing() failed to locate channel");
     return -1;