Remove stale 'virtual' in DiscardableMemoryAllocator.

base/memory/discardable_memory_allocator_android.cc

Index: base/memory/discardable_memory_allocator_android.cc
diff --git a/base/memory/discardable_memory_allocator_android.cc b/base/memory/discardable_memory_allocator_android.cc
index 7ca5e7d18f4fbeb309d3c205312dd0bee4d767b1..aea9451185030a91092a66991201481f3d402ee2 100644
--- a/base/memory/discardable_memory_allocator_android.cc
+++ b/base/memory/discardable_memory_allocator_android.cc
@@ -124,7 +124,7 @@ class DiscardableMemoryAllocator::AshmemRegion {
     return make_scoped_ptr(new AshmemRegion(fd, size, base, allocator));
   }
 
-  virtual ~AshmemRegion() {
+  ~AshmemRegion() {
     const bool result = internal::CloseAshmemRegion(fd_, size_, base_);
     DCHECK(result);
   }