This CL is due the thread I have made on chromium-dev:...

base/stack_container.h

 // Copyright (c) 2006-2008 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.
 
 #ifndef BASE_STACK_CONTAINER_H__
 #define BASE_STACK_CONTAINER_H__
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/thread_collision_warner.h"
 
 // This allocator can be used with STL containers to provide a stack buffer
 // from which to allocate memory and overflows onto the heap. This stack buffer
 // would be allocated on the stack and allows us to avoid heap operations in
 // some situations.
 //
 // STL likes to make copies of allocators, so the allocator itself can't hold
 // the data. Instead, we make the creator responsible for creating a
 // StackAllocator::Source which contains the data. Copying the allocator
 // merely copies the pointer to this shared source, so all allocators created
@@ skipping 123 matching lines @@
   // Danger: any copies of this made using the copy constructor must have
   // shorter lifetimes than the source. The copy will share the same allocator
   // and therefore the same stack buffer as the original. Use std::copy to
   // copy into a "real" container for longer-lived objects.
   ContainerType& container() { return container_; }
   const ContainerType& container() const { return container_; }
 
   // Support operator-> to get to the container. This allows nicer syntax like:
   //   StackContainer<...> foo;
   //   std::sort(foo->begin(), foo->end());
-  ContainerType* operator->() { return &container_; }
-  const ContainerType* operator->() const { return &container_; }
+  ContainerType* operator->() {
+    D_BOOK_CRITICAL_SECTION(arrow_operator_);
+    return &container_;
+  }
+  const ContainerType* operator->() const {
+    D_BOOK_CRITICAL_SECTION(arrow_operator_);
+    return &container_;
+  }
 
 #ifdef UNIT_TEST
   // Retrieves the stack source so that that unit tests can verify that the
   // buffer is being used properly.
   const typename Allocator::Source& stack_data() const {
     return stack_data_;
   }
 #endif
 
  protected:
   typename Allocator::Source stack_data_;
   Allocator allocator_;
   ContainerType container_;
 
+  D_DEFINE_CRITICAL_SECTION(arrow_operator_);
+
   DISALLOW_EVIL_CONSTRUCTORS(StackContainer);
 };
 
 // StackString
 template<size_t stack_capacity>
 class StackString : public StackContainer<
     std::basic_string<char,
                       std::char_traits<char>,
                       StackAllocator<char, stack_capacity> >,
     stack_capacity> {
@@ skipping 64 matching lines @@
   // Vectors are commonly indexed, which isn't very convenient even with
   // operator-> (using "->at()" does exception stuff we don't want).
   T& operator[](size_t i) { return this->container().operator[](i); }
   const T& operator[](size_t i) const { 
     return this->container().operator[](i); 
   }
 };
 
 #endif  // BASE_STACK_CONTAINER_H__