Replace NULL with nullptr in all C++ files.

webrtc/modules/video_capture/linux/video_capture_linux.cc

Index: webrtc/modules/video_capture/linux/video_capture_linux.cc
diff --git a/webrtc/modules/video_capture/linux/video_capture_linux.cc b/webrtc/modules/video_capture/linux/video_capture_linux.cc
index e8da74bb2f33c7228d262c241b9c887c6c66ec21..f2ac0d78f0061f138bbbeebb08698a9710600cfd 100644
--- a/webrtc/modules/video_capture/linux/video_capture_linux.cc
+++ b/webrtc/modules/video_capture/linux/video_capture_linux.cc
@@ -51,9 +51,7 @@ VideoCaptureModuleV4L2::VideoCaptureModuleV4L2()
       _currentFrameRate(-1),
       _captureStarted(false),
       _captureVideoType(kVideoI420),
-      _pool(NULL)
-{
-}
+      _pool(nullptr) {}
 
 int32_t VideoCaptureModuleV4L2::Init(const char* deviceUniqueIdUTF8)
 {
@@ -356,8 +354,8 @@ bool VideoCaptureModuleV4L2::AllocateVideoBuffers()
             return false;
         }
 
-        _pool[i].start = mmap(NULL, buffer.length, PROT_READ | PROT_WRITE, MAP_SHARED,
-                              _deviceFd, buffer.m.offset);
+        _pool[i].start = mmap(nullptr, buffer.length, PROT_READ | PROT_WRITE,
+                              MAP_SHARED, _deviceFd, buffer.m.offset);
 
         if (MAP_FAILED == _pool[i].start)
         {
@@ -418,7 +416,7 @@ bool VideoCaptureModuleV4L2::CaptureProcess()
     timeout.tv_sec = 1;
     timeout.tv_usec = 0;
 
-    retVal = select(_deviceFd + 1, &rSet, NULL, NULL, &timeout);
+    retVal = select(_deviceFd + 1, &rSet, nullptr, nullptr, &timeout);
     if (retVal < 0 && errno != EINTR) // continue if interrupted
     {
         // select failed