Mojo C++ bindings: introduce an optional array to store transferred interface IDs in messages.

mojo/public/cpp/bindings/lib/validation_context.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 "mojo/public/cpp/bindings/lib/validation_context.h"
 
 #include "base/logging.h"
 
 namespace mojo {
 namespace internal {
 
 ValidationContext::ValidationContext(const void* data,
                                      size_t data_num_bytes,
                                      size_t num_handles,
+                                     size_t num_associated_endpoint_handles,
                                      Message* message,
                                      const base::StringPiece& description,
                                      int stack_depth)
     : message_(message),
       description_(description),
       data_begin_(reinterpret_cast<uintptr_t>(data)),
       data_end_(data_begin_ + data_num_bytes),
       handle_begin_(0),
       handle_end_(static_cast<uint32_t>(num_handles)),
+      associated_endpoint_handle_begin_(0),
+      associated_endpoint_handle_end_(
+          static_cast<uint32_t>(num_associated_endpoint_handles)),
       stack_depth_(stack_depth) {
+  // Check whether the calculation of |data_end_| or static_cast from size_t to
+  // uint32_t causes overflow.
+  // They shouldn't happen but they do, set the corresponding range to empty.
   if (data_end_ < data_begin_) {
-    // The calculation of |data_end_| overflowed.
-    // It shouldn't happen but if it does, set the range to empty so
-    // IsValidRange() and ClaimMemory() always fail.
     NOTREACHED();
     data_end_ = data_begin_;
   }
   if (handle_end_ < num_handles) {
-    // Assigning |num_handles| to |handle_end_| overflowed.
-    // It shouldn't happen but if it does, set the handle index range to empty.
     NOTREACHED();
     handle_end_ = 0;
   }
+  if (associated_endpoint_handle_end_ < num_associated_endpoint_handles) {
+    NOTREACHED();
+    associated_endpoint_handle_end_ = 0;
+  }
 }
 
 ValidationContext::~ValidationContext() {
 }
 
 }  // namespace internal
 }  // namespace mojo