Replace NULL with nullptr in all C++ files.

webrtc/modules/desktop_capture/win/cursor.cc

Index: webrtc/modules/desktop_capture/win/cursor.cc
diff --git a/webrtc/modules/desktop_capture/win/cursor.cc b/webrtc/modules/desktop_capture/win/cursor.cc
index 304d5960d5ed7b3c450738ea31bf406b7cf23408..3cbe5e306bf3f1f82fbfd27bfb0a23ebb01553d0 100644
--- a/webrtc/modules/desktop_capture/win/cursor.cc
+++ b/webrtc/modules/desktop_capture/win/cursor.cc
@@ -114,7 +114,7 @@ MouseCursor* CreateMouseCursorFromHCursor(HDC dc, HCURSOR cursor) {
   if (!GetIconInfo(cursor, &iinfo)) {
     LOG_F(LS_ERROR) << "Unable to get cursor icon info. Error = "
                     << GetLastError();
-    return NULL;
+    return nullptr;
   }
 
   int hotspot_x = iinfo.xHotspot;
@@ -123,14 +123,14 @@ MouseCursor* CreateMouseCursorFromHCursor(HDC dc, HCURSOR cursor) {
   // Make sure the bitmaps will be freed.
   win::ScopedBitmap scoped_mask(iinfo.hbmMask);
   win::ScopedBitmap scoped_color(iinfo.hbmColor);
-  bool is_color = iinfo.hbmColor != NULL;
+  bool is_color = iinfo.hbmColor != nullptr;
 
   // Get |scoped_mask| dimensions.
   BITMAP bitmap_info;
   if (!GetObject(scoped_mask, sizeof(bitmap_info), &bitmap_info)) {
     LOG_F(LS_ERROR) << "Unable to get bitmap info. Error = "
                     << GetLastError();
-    return NULL;
+    return nullptr;
   }
 
   int width = bitmap_info.bmWidth;
@@ -158,7 +158,7 @@ MouseCursor* CreateMouseCursorFromHCursor(HDC dc, HCURSOR cursor) {
                  DIB_RGB_COLORS)) {
     LOG_F(LS_ERROR) << "Unable to get bitmap bits. Error = "
                     << GetLastError();
-    return NULL;
+    return nullptr;
   }
 
   uint32_t* mask_plane = mask_data.get();
@@ -178,7 +178,7 @@ MouseCursor* CreateMouseCursorFromHCursor(HDC dc, HCURSOR cursor) {
                    DIB_RGB_COLORS)) {
       LOG_F(LS_ERROR) << "Unable to get bitmap bits. Error = "
                       << GetLastError();
-      return NULL;
+      return nullptr;
     }
 
     // GetDIBits() does not provide any indication whether the bitmap has alpha