Replace NULL with nullptr in all C++ files.

webrtc/modules/video_coding/video_coding_robustness_unittest.cc

Index: webrtc/modules/video_coding/video_coding_robustness_unittest.cc
diff --git a/webrtc/modules/video_coding/video_coding_robustness_unittest.cc b/webrtc/modules/video_coding/video_coding_robustness_unittest.cc
index 55a05720c31137f76b07206fa6f60d2f2908cdd5..09302073f3593b5a6c54d06ef5c0ea54f5729f46 100644
--- a/webrtc/modules/video_coding/video_coding_robustness_unittest.cc
+++ b/webrtc/modules/video_coding/video_coding_robustness_unittest.cc
@@ -36,9 +36,9 @@ class VCMRobustnessTest : public ::testing::Test {
 
   virtual void SetUp() {
     clock_.reset(new SimulatedClock(0));
-    ASSERT_TRUE(clock_.get() != NULL);
+    ASSERT_TRUE(clock_.get() != nullptr);
     vcm_.reset(VideoCodingModule::Create(clock_.get(), &event_factory_));
-    ASSERT_TRUE(vcm_ != NULL);
+    ASSERT_TRUE(vcm_ != nullptr);
     const size_t kMaxNackListSize = 250;
     const int kMaxPacketAgeToNack = 450;
     vcm_->SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack, 0);