Pull the new r369476 of base library from Chromium

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

Change-Id: Ie6894cf65424cc5ad115110faccd51602b2d1234
Reviewed-on: https://weave-review.googlesource.com/2225
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/third_party/chromium/base/callback_forward.h b/third_party/chromium/base/callback_forward.h
index 262c306..a9a263a 100644
--- a/third_party/chromium/base/callback_forward.h
+++ b/third_party/chromium/base/callback_forward.h
@@ -10,7 +10,9 @@
 template <typename Sig>
 class Callback;
 
-typedef Callback<void(void)> Closure;
+// Syntactic sugar to make Callback<void()> easier to declare since it
+// will be used in a lot of APIs with delayed execution.
+using Closure = Callback<void()>;
 
 }  // namespace base