Add a GUID to base::SharedMemoryHandle.

base/memory/shared_memory.h

 // Copyright (c) 2012 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_MEMORY_SHARED_MEMORY_H_
 #define BASE_MEMORY_SHARED_MEMORY_H_
 
 #include <stddef.h>
 
 #include <string>
@@ skipping 45 matching lines @@
   // When opening an existing object, this has no effect.
   size_t size = 0;
 
   // If true, mappings might need to be made executable later.
   bool executable = false;
 
   // If true, the file can be shared read-only to a process.
   bool share_read_only = false;
 };
 
-// Platform abstraction for shared memory.  Provides a C++ wrapper
-// around the OS primitive for a memory mapped file.
+// Platform abstraction for shared memory.
+// SharedMemory consumes a SharedMemoryHandle [potentially one that it created]
+// to map a shared memory OS resource into the virtual address space of the
+// current process.
 class BASE_EXPORT SharedMemory {
  public:
   SharedMemory();
 
 #if defined(OS_WIN)
   // Similar to the default constructor, except that this allows for
   // calling LockDeprecated() to acquire the named mutex before either Create or
   // Open are called on Windows.
   explicit SharedMemory(const std::wstring& name);
 #endif
@@ skipping 183 matching lines @@
   void*              memory_;
   bool               read_only_;
   size_t             requested_size_;
 
   DISALLOW_COPY_AND_ASSIGN(SharedMemory);
 };
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_SHARED_MEMORY_H_