Combine 'pssh' parsing routines.

media/formats/mp4/box_reader.h

Index: media/formats/mp4/box_reader.h
diff --git a/media/formats/mp4/box_reader.h b/media/formats/mp4/box_reader.h
index 6b59361612459d84e29448c3b19b43595ab98cce..d70aead5a5e3320a36d9263f5173bedc468bc665 100644
--- a/media/formats/mp4/box_reader.h
+++ b/media/formats/mp4/box_reader.h
@@ -101,6 +101,9 @@ class MEDIA_EXPORT BoxReader : public BufferReader {
                                int* box_size,
                                bool* err) WARN_UNUSED_RESULT;
 
+  static BoxReader* ReadConcatentatedBoxes(const uint8* buf,
+                                           const int buf_size);
+
   // Returns true if |type| is recognized to be a top-level box, false
   // otherwise. This returns true for some boxes which we do not parse.
   // Helpful in debugging misaligned appends.
@@ -148,7 +151,10 @@ class MEDIA_EXPORT BoxReader : public BufferReader {
   const LogCB& log_cb() const { return log_cb_; }
 
  private:
-  BoxReader(const uint8* buf, const int size, const LogCB& log_cb);
+  BoxReader(const uint8* buf,
+            const int size,
+            const LogCB& log_cb,
+            bool enforce_size_check);
 
   // Must be called immediately after init. If the return is false, this
   // indicates that the box header and its contents were not available in the
@@ -170,6 +176,10 @@ class MEDIA_EXPORT BoxReader : public BufferReader {
   // valid if scanned_ is true.
   ChildMap children_;
   bool scanned_;
+
+  // Set to true if the buffer provided to the reader must contain all the bytes
+  // as specified by the box header.
+  bool enforce_size_check_;
 };
 
 // Template definitions
@@ -207,8 +217,9 @@ bool BoxReader::ReadAllChildren(std::vector<T>* children) {
   scanned_ = true;
 
   bool err = false;
-  while (pos() < size()) {
-    BoxReader child_reader(&buf_[pos_], size_ - pos_, log_cb_);
+  while (pos_ < size_) {
+    BoxReader child_reader(&buf_[pos_], size_ - pos_, log_cb_,
+                           enforce_size_check_);
     if (!child_reader.ReadHeader(&err)) break;
     T child;
     RCHECK(child.Parse(&child_reader));