Replace NULL with nullptr in all C++ files.

webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc

Index: webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
diff --git a/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc b/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
index cc4c602b18f0150815e3867138e934272b153e23..a817e12f49a09aeed071da3aee07b183711b2eaa 100644
--- a/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
+++ b/webrtc/sdk/android/src/jni/androidmediaencoder_jni.cc
@@ -298,7 +298,7 @@ MediaCodecVideoEncoder::MediaCodecVideoEncoder(JNIEnv* jni,
                                                const cricket::VideoCodec& codec,
                                                jobject egl_context)
     : codec_(codec),
-      callback_(NULL),
+      callback_(nullptr),
       codec_thread_(new Thread()),
       j_media_codec_video_encoder_class_(
           jni,
@@ -322,7 +322,7 @@ MediaCodecVideoEncoder::MediaCodecVideoEncoder(JNIEnv* jni,
   // |codec_thread_|, or from any thread holding the |_sendCritSect| described
   // in the bug, we have a problem.  For now work around that with a dedicated
   // thread.
-  codec_thread_->SetName("MediaCodecVideoEncoder", NULL);
+  codec_thread_->SetName("MediaCodecVideoEncoder", nullptr);
   RTC_CHECK(codec_thread_->Start()) << "Failed to start MediaCodecVideoEncoder";
   codec_thread_checker_.DetachFromThread();
   jclass j_output_buffer_info_class =
@@ -371,7 +371,7 @@ MediaCodecVideoEncoder::MediaCodecVideoEncoder(JNIEnv* jni,
     ALOGW << "MediaCodecVideoEncoder ctor failed.";
     ProcessHWErrorOnCodecThread(true /* reset_if_fallback_unavailable */);
   }
-  srand(time(NULL));
+  srand(time(nullptr));
   AllowBlockingCalls();
 }
 
@@ -379,8 +379,8 @@ int32_t MediaCodecVideoEncoder::InitEncode(
     const webrtc::VideoCodec* codec_settings,
     int32_t /* number_of_cores */,
     size_t /* max_payload_size */) {
-  if (codec_settings == NULL) {
-    ALOGE << "NULL VideoCodec instance";
+  if (codec_settings == nullptr) {
+    ALOGE << "null VideoCodec instance";
     return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
   }
   // Factory should guard against other codecs being used with us.