More clear comment for ValidateStructHeader.

mojo/public/cpp/bindings/lib/bindings_serialization.cc

 // Copyright 2013 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 "mojo/public/cpp/bindings/lib/bindings_serialization.h"
 
 #include <assert.h>
 
 #include "mojo/public/cpp/bindings/lib/bindings_internal.h"
 #include "mojo/public/cpp/bindings/lib/bounds_checker.h"
@@ skipping 66 matching lines @@
   }
   assert(handle->value() < handles->size());
   // Just leave holes in the vector so we don't screw up other indices.
   *handle = FetchAndReset(&handles->at(handle->value()));
 }
 
 bool ValidateStructHeader(const void* data,
                           uint32_t min_num_bytes,
                           uint32_t min_num_fields,
                           BoundsChecker* bounds_checker) {
+  assert(min_num_bytes >= sizeof(StructHeader));
+
   if (!IsAligned(data)) {
     ReportValidationError(VALIDATION_ERROR_MISALIGNED_OBJECT);
     return false;
   }
   if (!bounds_checker->IsValidRange(data, sizeof(StructHeader))) {
     ReportValidationError(VALIDATION_ERROR_ILLEGAL_MEMORY_RANGE);
     return false;
   }
 
   const StructHeader* header = static_cast<const StructHeader*>(data);
@@ skipping 10 matching lines @@
   if (!bounds_checker->ClaimMemory(data, header->num_bytes)) {
     ReportValidationError(VALIDATION_ERROR_ILLEGAL_MEMORY_RANGE);
     return false;
   }
 
   return true;
 }
 
 }  // namespace internal
 }  // namespace mojo