Upgrade AlignedMemory to support dynamic allocations.

base/compiler_specific.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_COMPILER_SPECIFIC_H_
 #define BASE_COMPILER_SPECIFIC_H_
 
 #include "build/build_config.h"
 
 #if defined(COMPILER_MSVC)
@@ skipping 96 matching lines @@
 // Specify memory alignment for structs, classes, etc.
 // Use like:
 //   class ALIGNAS(16) MyClass { ... }
 //   ALIGNAS(16) int array[4];
 #if defined(COMPILER_MSVC)
 #define ALIGNAS(byte_alignment) __declspec(align(byte_alignment))
 #elif defined(COMPILER_GCC)
 #define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
 #endif
 
-// Return the byte alignment of the given type (available at compile time).
+// Return the byte alignment of the given type (available at compile time).  Use
+// sizeof(type) prior to checking __alignof to workaround Visual C++ bug:
+// http://connect.microsoft.com/VisualStudio/feedback/details/682695/c-alignof-fails-to-properly-evalute-alignment-of-dependent-types
 // Use like:
 //   ALIGNOF(int32)  // this would be 4
 #if defined(COMPILER_MSVC)
-#define ALIGNOF(type) __alignof(type)
+#define ALIGNOF(type) (sizeof(type) - sizeof(type) + __alignof(type))
 #elif defined(COMPILER_GCC)
 #define ALIGNOF(type) __alignof__(type)
 #endif
 
 // Annotate a virtual method indicating it must be overriding a virtual
 // method in the parent class.
 // Use like:
 //   virtual void foo() OVERRIDE;
 #if defined(COMPILER_MSVC)
 #define OVERRIDE override
@@ skipping 26 matching lines @@
 #endif
 
 // WPRINTF_FORMAT is the same, but for wide format strings.
 // This doesn't appear to yet be implemented in any compiler.
 // See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38308 .
 #define WPRINTF_FORMAT(format_param, dots_param)
 // If available, it would look like:
 //   __attribute__((format(wprintf, format_param, dots_param)))
 
 #endif  // BASE_COMPILER_SPECIFIC_H_