libchrome: Uprev the library to r369476 from Chromium

Pulled the latest and greatest version of libchrome from Chromium.

The merge was done against r369476 which corresponds to git commit
0471d0e2e2ef4a544a63481a389e1df33ea7c00a of Jan 14, 2016

Notable changes are:
- base::scoped_ptr<T> is now almost identical to std::unique_ptr<T>
  No Pass() method, now std::move() is used on scoped pointers
- basictypes.h is removed and custom int types such as int32 are now
  replaced with the standard int32_t and similar from <stdint.h>
- String utility functions are cleaned up/refactored. Now all are in
  base:: namespace, many now return values rather than take pointers
  for results, ambiguous Booleans are replaced with enums, such as:
    base::StartsWithASCII(current_url, "https://", false);
  now is:
    base::StartsWith(current_url, "https://",
                     base::CompareCase::INSENSITIVE_ASCII);
- COMPILE_ASSERT() is now replaced with standard static_assert()
- Numeric range constants such as kuint64max are removed in favor of
  standard <limits> constructs such as std::numeric_limits<uint64_t>::max()
- base::Value and derived classes use scoped_ptr<> more and support
  for raw pointers to base::Value is deprecated and/or removed in
  many places.
- base::MessageLoopProxy is completely removed (was marked deprecated before)
- base::MessageLoop::Quit() and QuitClosure are renamed to QuitWhenIdle
  and QuitWhenIdleClosure for more semantic clarity.

Change-Id: I1f5436d253a0a32b2299160a76993752d818736f
diff --git a/crypto/symmetric_key.h b/crypto/symmetric_key.h
index 996c592..14f74ae 100644
--- a/crypto/symmetric_key.h
+++ b/crypto/symmetric_key.h
@@ -5,9 +5,12 @@
 #ifndef CRYPTO_SYMMETRIC_KEY_H_
 #define CRYPTO_SYMMETRIC_KEY_H_
 
+#include <stddef.h>
+
 #include <string>
 
-#include "base/basictypes.h"
+#include "base/macros.h"
+#include "build/build_config.h"
 #include "crypto/crypto_export.h"
 
 #if defined(NACL_WIN64)