diff --git a/media/mp4/box_definitions.cc b/media/mp4/box_definitions.cc
index d69d6ae9fa..460fe9f49b 100644
--- a/media/mp4/box_definitions.cc
+++ b/media/mp4/box_definitions.cc
@@ -1595,6 +1595,121 @@ uint32 TrackFragmentRun::ComputeSize() {
   return atom_size;
 }
 
+SampleToGroup::SampleToGroup() : grouping_type(0), grouping_type_parameter(0) {}
+SampleToGroup::~SampleToGroup() {}
+FourCC SampleToGroup::BoxType() const { return FOURCC_SBGP; }
+
+bool SampleToGroup::ReadWrite(BoxBuffer* buffer) {
+  RCHECK(FullBox::ReadWrite(buffer) &&
+         buffer->ReadWriteUInt32(&grouping_type));
+  if (version == 1)
+    RCHECK(buffer->ReadWriteUInt32(&grouping_type_parameter));
+
+  if (grouping_type != FOURCC_SEIG) {
+    DCHECK(buffer->Reading());
+    DLOG(WARNING) << "Sample group '" << grouping_type << "' is not supported.";
+    return true;
+  }
+
+  uint32 count = entries.size();
+  RCHECK(buffer->ReadWriteUInt32(&count));
+  entries.resize(count);
+  for (uint32 i = 0; i < count; ++i) {
+    RCHECK(buffer->ReadWriteUInt32(&entries[i].sample_count) &&
+           buffer->ReadWriteUInt32(&entries[i].group_description_index));
+  }
+  return true;
+}
+
+uint32 SampleToGroup::ComputeSize() {
+  // This box is optional. Skip it if it is not used.
+  atom_size = 0;
+  if (!entries.empty()) {
+    atom_size = kFullBoxSize + sizeof(grouping_type) +
+                (version == 1 ? sizeof(grouping_type_parameter) : 0) +
+                sizeof(uint32) + entries.size() * sizeof(entries[0]);
+  }
+  return atom_size;
+}
+
+CencSampleEncryptionInfoEntry::CencSampleEncryptionInfoEntry()
+    : is_encrypted(false), iv_size(0) {
+}
+CencSampleEncryptionInfoEntry::~CencSampleEncryptionInfoEntry() {};
+
+SampleGroupDescription::SampleGroupDescription() : grouping_type(0) {}
+SampleGroupDescription::~SampleGroupDescription() {}
+FourCC SampleGroupDescription::BoxType() const { return FOURCC_SGPD; }
+
+bool SampleGroupDescription::ReadWrite(BoxBuffer* buffer) {
+  RCHECK(FullBox::ReadWrite(buffer) &&
+         buffer->ReadWriteUInt32(&grouping_type));
+
+  if (grouping_type != FOURCC_SEIG) {
+    DCHECK(buffer->Reading());
+    DLOG(WARNING) << "Sample group '" << grouping_type << "' is not supported.";
+    return true;
+  }
+
+  const size_t kKeyIdSize = 16;
+  const size_t kEntrySize = sizeof(uint32) + kKeyIdSize;
+  uint32 default_length = 0;
+  if (version == 1) {
+    if (buffer->Reading()) {
+      RCHECK(buffer->ReadWriteUInt32(&default_length));
+      RCHECK(default_length == 0 || default_length == kEntrySize);
+    } else {
+      default_length = kEntrySize;
+      RCHECK(buffer->ReadWriteUInt32(&default_length));
+    }
+  }
+
+  uint32 count = entries.size();
+  RCHECK(buffer->ReadWriteUInt32(&count));
+  entries.resize(count);
+  for (uint32 i = 0; i < count; ++i) {
+    if (version == 1) {
+      if (buffer->Reading() && default_length == 0) {
+        uint32 description_length = 0;
+        RCHECK(buffer->ReadWriteUInt32(&description_length));
+        RCHECK(description_length == kEntrySize);
+      }
+    }
+
+    if (!buffer->Reading())
+      RCHECK(entries[i].key_id.size() == kKeyIdSize);
+
+    uint8 flag = entries[i].is_encrypted ? 1 : 0;
+    RCHECK(buffer->IgnoreBytes(2) &&  // reserved.
+           buffer->ReadWriteUInt8(&flag) &&
+           buffer->ReadWriteUInt8(&entries[i].iv_size) &&
+           buffer->ReadWriteVector(&entries[i].key_id, kKeyIdSize));
+
+    if (buffer->Reading()) {
+      entries[i].is_encrypted = (flag != 0);
+      if (entries[i].is_encrypted) {
+        RCHECK(entries[i].iv_size == 8 || entries[i].iv_size == 16);
+      } else {
+        RCHECK(entries[i].iv_size == 0);
+      }
+    }
+  }
+  return true;
+}
+
+uint32 SampleGroupDescription::ComputeSize() {
+  // This box is optional. Skip it if it is not used.
+  atom_size = 0;
+  if (!entries.empty()) {
+    const size_t kKeyIdSize = 16;
+    const size_t kEntrySize = sizeof(uint32) + kKeyIdSize;
+    atom_size = kFullBoxSize + sizeof(grouping_type) +
+                (version == 1 ? sizeof(uint32) : 0) +
+                sizeof(uint32) + entries.size() * kEntrySize;
+  }
+  return atom_size;
+}
+
 TrackFragment::TrackFragment() {}
 TrackFragment::~TrackFragment() {}
 FourCC TrackFragment::BoxType() const { return FOURCC_TRAF; }
@@ -1608,9 +1723,46 @@ bool TrackFragment::ReadWrite(BoxBuffer* buffer) {
   if (buffer->Reading()) {
     DCHECK(buffer->reader());
     RCHECK(buffer->reader()->TryReadChildren(&runs));
+
+    while (sample_to_group.grouping_type != FOURCC_SEIG &&
+           buffer->reader()->ChildExist(&sample_to_group)) {
+      RCHECK(buffer->reader()->ReadChild(&sample_to_group));
+    }
+    while (sample_group_description.grouping_type != FOURCC_SEIG &&
+           buffer->reader()->ChildExist(&sample_group_description)) {
+      RCHECK(buffer->reader()->ReadChild(&sample_group_description));
+    }
+    if (sample_to_group.grouping_type == FOURCC_SEIG) {
+      // SampleGroupDescription box can appear in either 'moov...stbl' or
+      // 'moov.traf'. The first case is not supported for now, so we require
+      // a companion SampleGroupDescription box to coexist with the
+      // SampleToGroup box.
+      if (sample_group_description.grouping_type != FOURCC_SEIG) {
+        NOTIMPLEMENTED()
+            << "SampleGroupDescription box in 'moov' is not supported.";
+        return false;
+      }
+      for (std::vector<SampleToGroupEntry>::iterator it =
+               sample_to_group.entries.begin();
+           it != sample_to_group.entries.end();
+           ++it) {
+        if ((it->group_description_index & 0x10000) == 0) {
+          NOTIMPLEMENTED()
+              << "SampleGroupDescription box in 'moov' is not supported.";
+          return false;
+        }
+        it->group_description_index &= 0x0FFFF;
+        RCHECK(it->group_description_index <=
+               sample_group_description.entries.size());
+      }
+    } else {
+      RCHECK(sample_group_description.grouping_type != FOURCC_SEIG);
+    }
   } else {
     for (uint32 i = 0; i < runs.size(); ++i)
       RCHECK(runs[i].ReadWrite(buffer));
+    RCHECK(buffer->TryReadWriteChild(&sample_to_group) &&
+           buffer->TryReadWriteChild(&sample_group_description));
   }
   return buffer->TryReadWriteChild(&auxiliary_size) &&
          buffer->TryReadWriteChild(&auxiliary_offset);
@@ -1618,6 +1770,8 @@ bool TrackFragment::ReadWrite(BoxBuffer* buffer) {
 
 uint32 TrackFragment::ComputeSize() {
   atom_size = kBoxSize + header.ComputeSize() + decode_time.ComputeSize() +
+              sample_to_group.ComputeSize() +
+              sample_group_description.ComputeSize() +
               auxiliary_size.ComputeSize() + auxiliary_offset.ComputeSize();
   for (uint32 i = 0; i < runs.size(); ++i)
     atom_size += runs[i].ComputeSize();
diff --git a/media/mp4/box_definitions.h b/media/mp4/box_definitions.h
index a56388e2cb..e11baea633 100644
--- a/media/mp4/box_definitions.h
+++ b/media/mp4/box_definitions.h
@@ -492,14 +492,50 @@ struct TrackFragmentRun : FullBox {
   std::vector<int32> sample_composition_time_offsets;
 };
 
+struct SampleToGroupEntry {
+  enum GroupDescriptionIndexBase {
+    kTrackGroupDescriptionIndexBase = 0,
+    kTrackFragmentGroupDescriptionIndexBase = 0x10000,
+  };
+
+  uint32 sample_count;
+  uint32 group_description_index;
+};
+
+struct SampleToGroup : FullBox {
+  DECLARE_BOX_METHODS(SampleToGroup);
+
+  uint32 grouping_type;
+  uint32 grouping_type_parameter;  // Version 1 only.
+  std::vector<SampleToGroupEntry> entries;
+};
+
+struct CencSampleEncryptionInfoEntry {
+  CencSampleEncryptionInfoEntry();
+  ~CencSampleEncryptionInfoEntry();
+
+  bool is_encrypted;
+  uint8 iv_size;
+  std::vector<uint8> key_id;
+};
+
+struct SampleGroupDescription : FullBox {
+  DECLARE_BOX_METHODS(SampleGroupDescription);
+
+  uint32 grouping_type;
+  std::vector<CencSampleEncryptionInfoEntry> entries;
+};
+
 struct TrackFragment : Box {
   DECLARE_BOX_METHODS(TrackFragment);
 
   TrackFragmentHeader header;
   std::vector<TrackFragmentRun> runs;
   TrackFragmentDecodeTime decode_time;
-  SampleAuxiliaryInformationOffset auxiliary_offset;
+  SampleToGroup sample_to_group;
+  SampleGroupDescription sample_group_description;
   SampleAuxiliaryInformationSize auxiliary_size;
+  SampleAuxiliaryInformationOffset auxiliary_offset;
 };
 
 struct MovieFragment : Box {
diff --git a/media/mp4/box_definitions_comparison.h b/media/mp4/box_definitions_comparison.h
index 5441ae3718..df71db91d1 100644
--- a/media/mp4/box_definitions_comparison.h
+++ b/media/mp4/box_definitions_comparison.h
@@ -303,6 +303,32 @@ inline bool operator==(const TrackFragmentRun& lhs,
              rhs.sample_composition_time_offsets;
 }
 
+inline bool operator==(const SampleToGroupEntry& lhs,
+                       const SampleToGroupEntry& rhs) {
+  return lhs.sample_count == rhs.sample_count &&
+         lhs.group_description_index == rhs.group_description_index;
+}
+
+inline bool operator==(const SampleToGroup& lhs,
+                       const SampleToGroup& rhs) {
+  return lhs.grouping_type == rhs.grouping_type &&
+         lhs.grouping_type_parameter == rhs.grouping_type_parameter &&
+         lhs.entries == rhs.entries;
+}
+
+inline bool operator==(const CencSampleEncryptionInfoEntry& lhs,
+                       const CencSampleEncryptionInfoEntry& rhs) {
+  return lhs.is_encrypted == rhs.is_encrypted &&
+         lhs.iv_size == rhs.iv_size &&
+         lhs.key_id == rhs.key_id;
+}
+
+inline bool operator==(const SampleGroupDescription& lhs,
+                       const SampleGroupDescription& rhs) {
+  return lhs.grouping_type == rhs.grouping_type &&
+         lhs.entries == rhs.entries;
+}
+
 inline bool operator==(const TrackFragment& lhs, const TrackFragment& rhs) {
   return lhs.header == rhs.header && lhs.runs == rhs.runs &&
          lhs.decode_time == rhs.decode_time &&
diff --git a/media/mp4/box_definitions_unittest.cc b/media/mp4/box_definitions_unittest.cc
index cf29e02d62..ddf6d0002b 100644
--- a/media/mp4/box_definitions_unittest.cc
+++ b/media/mp4/box_definitions_unittest.cc
@@ -103,7 +103,7 @@ class BoxDefinitionsTestGeneral : public testing::Test {
   void Modify(Box* box) {}
 
   // Is this box optional?
-  bool IsOptional(Box* box) { return false; }
+  bool IsOptional(const Box* box) { return false; }
 
   // Non-full box does not have version field.
   uint8 GetAndClearVersion(Box* box) { return 0; }
@@ -625,6 +625,37 @@ class BoxDefinitionsTestGeneral : public testing::Test {
     trun->version = 1;
   }
 
+  void Fill(SampleToGroup* sbgp) {
+    sbgp->grouping_type = FOURCC_SEIG;
+    sbgp->entries.resize(2);
+    sbgp->entries[0].sample_count = 3;
+    sbgp->entries[0].group_description_index = 0x10002;
+    sbgp->entries[0].sample_count = 1212;
+    sbgp->entries[0].group_description_index = 0x10001;
+  }
+
+  void Modify(SampleToGroup* sbgp) {
+    sbgp->entries.resize(1);
+    sbgp->entries[0].group_description_index = 0x10001;
+  }
+
+  void Fill(SampleGroupDescription* sgpd) {
+    sgpd->grouping_type = FOURCC_SEIG;
+    sgpd->entries.resize(2);
+    sgpd->entries[0].is_encrypted = true;
+    sgpd->entries[0].iv_size = 8;
+    sgpd->entries[0].key_id.assign(kData16Bytes,
+                                   kData16Bytes + arraysize(kData16Bytes));
+    sgpd->entries[1].is_encrypted = false;
+    sgpd->entries[1].iv_size = 0;
+    sgpd->entries[1].key_id.resize(16);
+  }
+
+  void Modify(SampleGroupDescription* sbgp) {
+    sbgp->entries.resize(1);
+    sbgp->entries[0].key_id[4] = 88;
+  }
+
   void Fill(TrackFragment* traf) {
     Fill(&traf->header);
     traf->runs.resize(1);
@@ -680,18 +711,20 @@ class BoxDefinitionsTestGeneral : public testing::Test {
     sidx->version = 1;
   }
 
-  bool IsOptional(SampleAuxiliaryInformationOffset* box) { return true; }
-  bool IsOptional(SampleAuxiliaryInformationSize* box) { return true; }
-  bool IsOptional(ProtectionSchemeInfo* box) { return true; }
-  bool IsOptional(EditList* box) { return true; }
-  bool IsOptional(Edit* box) { return true; }
-  bool IsOptional(AVCDecoderConfigurationRecord* box) { return true; }
-  bool IsOptional(PixelAspectRatioBox* box) { return true; }
-  bool IsOptional(ElementaryStreamDescriptor* box) { return true; }
-  bool IsOptional(CompositionTimeToSample* box) { return true; }
-  bool IsOptional(SyncSample* box) { return true; }
-  bool IsOptional(MovieExtendsHeader* box) { return true; }
-  bool IsOptional(MovieExtends* box) { return true; }
+  bool IsOptional(const SampleAuxiliaryInformationOffset* box) { return true; }
+  bool IsOptional(const SampleAuxiliaryInformationSize* box) { return true; }
+  bool IsOptional(const ProtectionSchemeInfo* box) { return true; }
+  bool IsOptional(const EditList* box) { return true; }
+  bool IsOptional(const Edit* box) { return true; }
+  bool IsOptional(const AVCDecoderConfigurationRecord* box) { return true; }
+  bool IsOptional(const PixelAspectRatioBox* box) { return true; }
+  bool IsOptional(const ElementaryStreamDescriptor* box) { return true; }
+  bool IsOptional(const CompositionTimeToSample* box) { return true; }
+  bool IsOptional(const SyncSample* box) { return true; }
+  bool IsOptional(const MovieExtendsHeader* box) { return true; }
+  bool IsOptional(const MovieExtends* box) { return true; }
+  bool IsOptional(const SampleToGroup* box) { return true; }
+  bool IsOptional(const SampleGroupDescription* box) { return true; }
 
  protected:
   scoped_ptr<BufferWriter> buffer_;
@@ -749,9 +782,15 @@ typedef testing::Types<
     MovieFragment,
     SegmentIndex> Boxes;
 
-TYPED_TEST_CASE(BoxDefinitionsTestGeneral, Boxes);
+// GTEST support a maximum of 50 types in the template list, so we have to
+// break it into two groups.
+typedef testing::Types<
+    SampleToGroup,
+    SampleGroupDescription> Boxes2;
 
-TYPED_TEST(BoxDefinitionsTestGeneral, WriteReadbackCompare) {
+TYPED_TEST_CASE_P(BoxDefinitionsTestGeneral);
+
+TYPED_TEST_P(BoxDefinitionsTestGeneral, WriteReadbackCompare) {
   TypeParam box;
   LOG(INFO) << "Processing " << FourCCToString(box.BoxType());
   this->Fill(&box);
@@ -762,7 +801,7 @@ TYPED_TEST(BoxDefinitionsTestGeneral, WriteReadbackCompare) {
   ASSERT_EQ(box, box_readback);
 }
 
-TYPED_TEST(BoxDefinitionsTestGeneral, WriteModifyWrite) {
+TYPED_TEST_P(BoxDefinitionsTestGeneral, WriteModifyWrite) {
   TypeParam box;
   LOG(INFO) << "Processing " << FourCCToString(box.BoxType());
   this->Fill(&box);
@@ -783,7 +822,7 @@ TYPED_TEST(BoxDefinitionsTestGeneral, WriteModifyWrite) {
   ASSERT_EQ(box, box_readback);
 }
 
-TYPED_TEST(BoxDefinitionsTestGeneral, Empty) {
+TYPED_TEST_P(BoxDefinitionsTestGeneral, Empty) {
   TypeParam box;
   LOG(INFO) << "Processing " << FourCCToString(box.BoxType());
   if (this->IsOptional(&box)) {
@@ -793,6 +832,18 @@ TYPED_TEST(BoxDefinitionsTestGeneral, Empty) {
   }
 }
 
+REGISTER_TYPED_TEST_CASE_P(BoxDefinitionsTestGeneral,
+                           WriteReadbackCompare,
+                           WriteModifyWrite,
+                           Empty);
+
+INSTANTIATE_TYPED_TEST_CASE_P(BoxDefinitionTypedTests,
+                              BoxDefinitionsTestGeneral,
+                              Boxes);
+INSTANTIATE_TYPED_TEST_CASE_P(BoxDefinitionTypedTests2,
+                              BoxDefinitionsTestGeneral,
+                              Boxes2);
+
 // Test other cases of box input.
 class BoxDefinitionsTest : public BoxDefinitionsTestGeneral<Box> {};
 
diff --git a/media/mp4/fourccs.h b/media/mp4/fourccs.h
index 9c3e2bd664..ee86dd7a3b 100644
--- a/media/mp4/fourccs.h
+++ b/media/mp4/fourccs.h
@@ -56,9 +56,12 @@ enum FourCC {
   FOURCC_PSSH = 0x70737368,
   FOURCC_SAIO = 0x7361696f,
   FOURCC_SAIZ = 0x7361697a,
+  FOURCC_SBGP = 0x73626770,
   FOURCC_SCHI = 0x73636869,
   FOURCC_SCHM = 0x7363686d,
   FOURCC_SDTP = 0x73647470,
+  FOURCC_SEIG = 0x73656967,
+  FOURCC_SGPD = 0x73677064,
   FOURCC_SIDX = 0x73696478,
   FOURCC_SINF = 0x73696e66,
   FOURCC_SKIP = 0x736b6970,