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/observer_list.h b/third_party/chromium/base/observer_list.h
index 3baf910..bb76091 100644
--- a/third_party/chromium/base/observer_list.h
+++ b/third_party/chromium/base/observer_list.h
@@ -5,12 +5,14 @@
 #ifndef BASE_OBSERVER_LIST_H_
 #define BASE_OBSERVER_LIST_H_
 
+#include <stddef.h>
+
 #include <algorithm>
 #include <limits>
 #include <vector>
 
-#include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -152,8 +154,8 @@
 template <class ObserverType>
 void ObserverListBase<ObserverType>::AddObserver(ObserverType* obs) {
   DCHECK(obs);
-  if (std::find(observers_.begin(), observers_.end(), obs)
-      != observers_.end()) {
+  auto it = std::find(observers_.begin(), observers_.end(), obs);
+  if (it != observers_.end()) {
     NOTREACHED() << "Observers can only be added once!";
     return;
   }