Restrict volatile section of block header.

base/metrics/persistent_memory_allocator.h

Index: base/metrics/persistent_memory_allocator.h
diff --git a/base/metrics/persistent_memory_allocator.h b/base/metrics/persistent_memory_allocator.h
index 65d5a0eccbe7c26a350d7b7da2c6268aaf49d1d6..5c2c7049da9c10cc408e28b4a70e9a8a7c44652a 100644
--- a/base/metrics/persistent_memory_allocator.h
+++ b/base/metrics/persistent_memory_allocator.h
@@ -249,11 +249,12 @@ class BASE_EXPORT PersistentMemoryAllocator {
   // The shared metadata is always located at the top of the memory segment.
   // These convenience functions eliminate constant casting of the base
   // pointer within the code.
-  const volatile SharedMetadata* shared_meta() const {
-    return reinterpret_cast<const volatile SharedMetadata*>(mem_base_);
+  const SharedMetadata* shared_meta() const {
+    return reinterpret_cast<const SharedMetadata*>(
+        const_cast<const char*>(mem_base_));

[Alexei Svitkine (slow), 2016/02/05 19:31:32]

I don't understand why there's a const_cast here?

   }
-  volatile SharedMetadata* shared_meta() {
-    return reinterpret_cast<volatile SharedMetadata*>(mem_base_);
+  SharedMetadata* shared_meta() {
+    return reinterpret_cast<SharedMetadata*>(const_cast<char*>(mem_base_));
   }
 
   // Actual method for doing the allocation.