diff --git a/media/mp4/mp4_fragmenter.cc b/media/mp4/mp4_fragmenter.cc
index 283162663a..9cd555b338 100644
--- a/media/mp4/mp4_fragmenter.cc
+++ b/media/mp4/mp4_fragmenter.cc
@@ -19,7 +19,8 @@ const uint64 kInvalidTime = kuint64max;
 // otherwise it is a NOP. Return true if the table is optimized.
 template <typename T>
 bool OptimizeSampleEntries(std::vector<T>* entries, T* default_value) {
-  DCHECK(entries != NULL && default_value != NULL);
+  DCHECK(entries);
+  DCHECK(default_value);
   DCHECK(!entries->empty());
 
   typename std::vector<T>::const_iterator it = entries->begin();
@@ -54,8 +55,7 @@ MP4Fragmenter::MP4Fragmenter(TrackFragment* traf,
 MP4Fragmenter::~MP4Fragmenter() {}
 
 Status MP4Fragmenter::AddSample(scoped_refptr<MediaSample> sample) {
-  CHECK(sample->pts() >= sample->dts());
-  CHECK(sample->duration() > 0);
+  CHECK_GT(sample->duration(), 0);
 
   if (ShouldEncryptFragment()) {
     Status status = EncryptSample(sample);
diff --git a/media/mp4/mp4_general_segmenter.cc b/media/mp4/mp4_general_segmenter.cc
index dcf096943a..9e38f3f911 100644
--- a/media/mp4/mp4_general_segmenter.cc
+++ b/media/mp4/mp4_general_segmenter.cc
@@ -37,7 +37,8 @@ Status MP4GeneralSegmenter::Initialize(
   if (!status.ok())
     return status;
 
-  DCHECK(ftyp() != NULL && moov() != NULL);
+  DCHECK(ftyp());
+  DCHECK(moov());
   // Generate the output file with init segment.
   File* file = File::Open(options().output_file_name.c_str(), "w");
   if (file == NULL) {
@@ -73,7 +74,7 @@ Status MP4GeneralSegmenter::FinalizeSegment() {
   if (!status.ok())
     return status;
 
-  DCHECK(sidx() != NULL);
+  DCHECK(sidx());
   // earliest_presentation_time is the earliest presentation time of any
   // access unit in the reference stream in the first subsegment.
   // It will be re-calculated later when subsegments are finalized.
@@ -134,7 +135,9 @@ Status MP4GeneralSegmenter::FinalizeSegment() {
 }
 
 Status MP4GeneralSegmenter::WriteSegment() {
-  DCHECK(sidx() != NULL && fragment_buffer() != NULL && styp_ != NULL);
+  DCHECK(sidx());
+  DCHECK(fragment_buffer());
+  DCHECK(styp_);
 
   scoped_ptr<BufferWriter> buffer(new BufferWriter());
   File* file;
diff --git a/media/mp4/mp4_muxer.cc b/media/mp4/mp4_muxer.cc
index ae64f8f17b..93625fb6d7 100644
--- a/media/mp4/mp4_muxer.cc
+++ b/media/mp4/mp4_muxer.cc
@@ -119,7 +119,7 @@ Status MP4Muxer::Initialize() {
 }
 
 Status MP4Muxer::Finalize() {
-  DCHECK(segmenter_ != NULL);
+  DCHECK(segmenter_);
   Status segmenter_finalized = segmenter_->Finalize();
 
   if (!segmenter_finalized.ok())
@@ -131,7 +131,7 @@ Status MP4Muxer::Finalize() {
 
 Status MP4Muxer::AddSample(const MediaStream* stream,
                            scoped_refptr<MediaSample> sample) {
-  DCHECK(segmenter_ != NULL);
+  DCHECK(segmenter_);
   return segmenter_->AddSample(stream, sample);
 }
 
@@ -173,7 +173,7 @@ void MP4Muxer::GenerateVideoTrak(const VideoStreamInfo* video_info,
   sample_description.video_entries.push_back(video);
 
   if (IsEncryptionRequired()) {
-    DCHECK(encryptor_source() != NULL);
+    DCHECK(encryptor_source());
     // Add a second entry for clear content if needed.
     if (clear_lead_in_seconds() > 0)
       sample_description.video_entries.push_back(video);
@@ -213,7 +213,7 @@ void MP4Muxer::GenerateAudioTrak(const AudioStreamInfo* audio_info,
   sample_description.audio_entries.push_back(audio);
 
   if (IsEncryptionRequired()) {
-    DCHECK(encryptor_source() != NULL);
+    DCHECK(encryptor_source());
     // Add a second entry for clear content if needed.
     if (clear_lead_in_seconds() > 0)
       sample_description.audio_entries.push_back(audio);
@@ -225,13 +225,13 @@ void MP4Muxer::GenerateAudioTrak(const AudioStreamInfo* audio_info,
 }
 
 void MP4Muxer::GeneratePssh(ProtectionSystemSpecificHeader* pssh) {
-  DCHECK(encryptor_source() != NULL);
+  DCHECK(encryptor_source());
   pssh->system_id = encryptor_source()->key_system_id();
   pssh->data = encryptor_source()->pssh();
 }
 
 void MP4Muxer::GenerateSinf(ProtectionSchemeInfo* sinf, FourCC old_type) {
-  DCHECK(encryptor_source() != NULL);
+  DCHECK(encryptor_source());
   sinf->format.format = old_type;
   sinf->type.type = FOURCC_CENC;
   sinf->type.version = kCencSchemeVersion;
diff --git a/media/mp4/mp4_segmenter.cc b/media/mp4/mp4_segmenter.cc
index 110f49eaa5..d3c8fcf1aa 100644
--- a/media/mp4/mp4_segmenter.cc
+++ b/media/mp4/mp4_segmenter.cc
@@ -113,7 +113,8 @@ Status MP4Segmenter::Finalize() {
 Status MP4Segmenter::AddSample(const MediaStream* stream,
                                scoped_refptr<MediaSample> sample) {
   // Find the fragmenter for this stream.
-  DCHECK(stream != NULL && stream_map_.find(stream) != stream_map_.end());
+  DCHECK(stream);
+  DCHECK(stream_map_.find(stream) != stream_map_.end());
   uint32 stream_id = stream_map_[stream];
   MP4Fragmenter* fragmenter = fragmenters_[stream_id];
 
@@ -191,7 +192,7 @@ Status MP4Segmenter::FinalizeSegment() {
 }
 
 uint32 MP4Segmenter::GetReferenceStreamId() {
-  DCHECK(sidx_ != NULL);
+  DCHECK(sidx_);
   return sidx_->reference_id - 1;
 }
 
diff --git a/media/mp4/mp4_vod_segmenter.cc b/media/mp4/mp4_vod_segmenter.cc
index b09b4d42f6..aa67c0040c 100644
--- a/media/mp4/mp4_vod_segmenter.cc
+++ b/media/mp4/mp4_vod_segmenter.cc
@@ -111,7 +111,8 @@ Status MP4VODSegmenter::FinalizeSegment() {
   if (!status.ok())
     return status;
 
-  DCHECK(sidx() != NULL && fragment_buffer() != NULL);
+  DCHECK(sidx());
+  DCHECK(fragment_buffer());
   // sidx() contains pre-generated segment references with one reference per
   // fragment. In VOD, this segment is converted into a subsegment, i.e. one
   // reference, which contains all the fragments in sidx().