Run clang-modernize -use-nullptr over src/extensions/.

extensions/renderer/api/serial/data_sender_unittest.cc

Index: extensions/renderer/api/serial/data_sender_unittest.cc
diff --git a/extensions/renderer/api/serial/data_sender_unittest.cc b/extensions/renderer/api/serial/data_sender_unittest.cc
index 9f129e077fe23511d0d8b4bab785c518ce69c4c3..bf3b96a24353114c91e4b1d5ff07b15bd9b91b53 100644
--- a/extensions/renderer/api/serial/data_sender_unittest.cc
+++ b/extensions/renderer/api/serial/data_sender_unittest.cc
@@ -29,7 +29,7 @@ class DataSenderTest : public ApiTestBase {
   virtual void TearDown() OVERRIDE {
     if (receiver_.get()) {
       receiver_->ShutDown();
-      receiver_ = NULL;
+      receiver_ = nullptr;
     }
     EXPECT_FALSE(buffer_);
     buffer_.reset();