Add Common Encryption support to BMFF, including subsample decryption.

media/mp4/box_definitions.cc

Index: media/mp4/box_definitions.cc
diff --git a/media/mp4/box_definitions.cc b/media/mp4/box_definitions.cc
index 5d18c32182f0db20f236ed283af903a75fa213d5..fb9723006fb8aa7528092ddb9113d5bedc5a329d 100644
--- a/media/mp4/box_definitions.cc
+++ b/media/mp4/box_definitions.cc
@@ -85,7 +85,7 @@ SchemeType::~SchemeType() {}
 FourCC SchemeType::BoxType() const { return FOURCC_SCHM; }
 
 bool SchemeType::Parse(BoxReader* reader) {
-  RCHECK(reader->SkipBytes(4) &&
+  RCHECK(reader->ReadFullBoxHeader() &&
          reader->ReadFourCC(&type) &&
          reader->Read4(&version));
   RCHECK(type == FOURCC_CENC);
@@ -100,7 +100,8 @@ FourCC TrackEncryption::BoxType() const { return FOURCC_TENC; }
 
 bool TrackEncryption::Parse(BoxReader* reader) {
   uint8 flag;
-  RCHECK(reader->SkipBytes(2) &&
+  RCHECK(reader->ReadFullBoxHeader() &&
+         reader->SkipBytes(2) &&
          reader->Read1(&flag) &&
          reader->Read1(&default_iv_size) &&
          reader->ReadVec(&default_kid, 16));
@@ -126,9 +127,10 @@ ProtectionSchemeInfo::~ProtectionSchemeInfo() {}
 FourCC ProtectionSchemeInfo::BoxType() const { return FOURCC_SINF; }
 
 bool ProtectionSchemeInfo::Parse(BoxReader* reader) {
-  return reader->ScanChildren() &&
+  RCHECK(reader->ScanChildren() &&
          reader->ReadChild(&type) &&
-         reader->ReadChild(&info);
+         reader->ReadChild(&info));
+  return true;
 }
 
 MovieHeader::MovieHeader()
@@ -362,19 +364,12 @@ bool VideoSampleEntry::Parse(BoxReader* reader) {
          reader->Read2(&height) &&
          reader->SkipBytes(50));
 
+  // TODO(strobe): Finalize format signaling for encrypted media
+  // (http://crbug.com/132351). For now, we assume that every video track is
+  // AVC, and that any track may have a Common Encryption header regardless of
+  // format.
   RCHECK(reader->ScanChildren());
-  if (format == FOURCC_ENCV) {
-    RCHECK(reader->ReadChild(&sinf));
-  }
-
-  // TODO(strobe): finalize format signaling for encrypted media
-  // (http://crbug.com/132351)
-  //
-  //  if (format == FOURCC_AVC1 ||
-  //      (format == FOURCC_ENCV &&
-  //       sinf.format.format == FOURCC_AVC1)) {
-    RCHECK(reader->ReadChild(&avcc));
-  //  }
+  RCHECK(reader->ReadChild(&avcc) && reader->MaybeReadChild(&sinf));
   return true;
 }
 
@@ -404,10 +399,8 @@ bool AudioSampleEntry::Parse(BoxReader* reader) {
   // Convert from 16.16 fixed point to integer
   samplerate >>= 16;
 
-  RCHECK(reader->ScanChildren());
-  if (format == FOURCC_ENCA) {
-    RCHECK(reader->ReadChild(&sinf));
-  }
+  RCHECK(reader->ScanChildren() &&
+         reader->MaybeReadChild(&sinf));
   return true;
 }