Replace NULL with nullptr or null in webrtc/audio/ and common_audio/.

webrtc/common_audio/vad/vad_core_unittest.cc

Index: webrtc/common_audio/vad/vad_core_unittest.cc
diff --git a/webrtc/common_audio/vad/vad_core_unittest.cc b/webrtc/common_audio/vad/vad_core_unittest.cc
index 43673ee62af81698ac9f8a3049ea020e5d63cbe5..ba53c560e23c33d14aa78dce52adf5f642d77074 100644
--- a/webrtc/common_audio/vad/vad_core_unittest.cc
+++ b/webrtc/common_audio/vad/vad_core_unittest.cc
@@ -24,10 +24,10 @@ TEST_F(VadTest, InitCore) {
   // Test WebRtcVad_InitCore().
   VadInstT* self = reinterpret_cast<VadInstT*>(malloc(sizeof(VadInstT)));
 
-  // NULL pointer test.
-  EXPECT_EQ(-1, WebRtcVad_InitCore(NULL));
+  // null pointer test.
+  EXPECT_EQ(-1, WebRtcVad_InitCore(nullptr));
 
-  // Verify return = 0 for non-NULL pointer.
+  // Verify return = 0 for non-null pointer.
   EXPECT_EQ(0, WebRtcVad_InitCore(self));
   // Verify init_flag is set.
   EXPECT_EQ(42, self->init_flag);
@@ -38,7 +38,7 @@ TEST_F(VadTest, InitCore) {
 TEST_F(VadTest, set_mode_core) {
   VadInstT* self = reinterpret_cast<VadInstT*>(malloc(sizeof(VadInstT)));
 
-  // TODO(bjornv): Add NULL pointer check if we take care of it in
+  // TODO(bjornv): Add null pointer check if we take care of it in
   // vad_core.c
 
   ASSERT_EQ(0, WebRtcVad_InitCore(self));
@@ -58,7 +58,7 @@ TEST_F(VadTest, CalcVad) {
   VadInstT* self = reinterpret_cast<VadInstT*>(malloc(sizeof(VadInstT)));
   int16_t speech[kMaxFrameLength];
 
-  // TODO(bjornv): Add NULL pointer check if we take care of it in
+  // TODO(bjornv): Add null pointer check if we take care of it in
   // vad_core.c
 
   // Test WebRtcVad_CalcVadXXkhz()