Use acquire/relase for delayed persistent allocations.

base/metrics/persistent_memory_allocator.cc

Index: base/metrics/persistent_memory_allocator.cc
diff --git a/base/metrics/persistent_memory_allocator.cc b/base/metrics/persistent_memory_allocator.cc
index 3c5198ae9eaaf18ecab312107239e6f5c82c0bb6..deb82ac1dbe28aa26d14ee98f48139b3068b3488 100644
--- a/base/metrics/persistent_memory_allocator.cc
+++ b/base/metrics/persistent_memory_allocator.cc
@@ -1133,7 +1133,7 @@ DelayedPersistentAllocation::~DelayedPersistentAllocation() {}
 void* DelayedPersistentAllocation::Get() const {
   // Relaxed operations are acceptable here because it's not protecting the
   // contents of the allocation in any way.
-  Reference ref = reference_->load(std::memory_order_relaxed);
+  Reference ref = reference_->load(std::memory_order_acquire);
   if (!ref) {
     ref = allocator_->Allocate(size_, type_);
     if (!ref)
@@ -1144,7 +1144,7 @@ void* DelayedPersistentAllocation::Get() const {
     // cannot be retried.
     Reference existing = 0;  // Must be mutable; receives actual value.
     if (reference_->compare_exchange_strong(existing, ref,
-                                            std::memory_order_relaxed,
+                                            std::memory_order_release,
                                             std::memory_order_relaxed)) {
       if (make_iterable_)
         allocator_->MakeIterable(ref);