Remove DCHECK since error is properly handled.

media/formats/mp4/box_reader.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/formats/mp4/box_reader.h"
 
 #include <stddef.h>
 #include <string.h>
 
 #include <algorithm>
@@ skipping 182 matching lines @@
 
   bool err = false;
   while (pos_ < size_) {
     BoxReader child(&buf_[pos_], size_ - pos_, media_log_, is_EOS_);
     if (!child.ReadHeader(&err)) break;
 
     children_.insert(std::pair<FourCC, BoxReader>(child.type(), child));
     pos_ += child.size();
   }
 
-  DCHECK(!err);
   return !err && pos_ == size_;
 }
 
 bool BoxReader::HasChild(Box* child) {
   DCHECK(scanned_);
   DCHECK(child);
   return children_.count(child->BoxType()) > 0;
 }
 
 bool BoxReader::ReadChild(Box* child) {
@@ skipping 68 matching lines @@
   }
 
   // Note that the pos_ head has advanced to the byte immediately after the
   // header, which is where we want it.
   size_ = size;
   return true;
 }
 
 }  // namespace mp4
 }  // namespace media