gpu: Assert that FencedAllocator is empty in destructor

gpu/command_buffer/client/fenced_allocator.cc

Index: gpu/command_buffer/client/fenced_allocator.cc
diff --git a/gpu/command_buffer/client/fenced_allocator.cc b/gpu/command_buffer/client/fenced_allocator.cc
index 4e405e94e7ad5626094fe9fb91ec365f00189835..80038571be9fccf4e5274101e0959c33aa2586c9 100644
--- a/gpu/command_buffer/client/fenced_allocator.cc
+++ b/gpu/command_buffer/client/fenced_allocator.cc
@@ -50,9 +50,9 @@ FencedAllocator::~FencedAllocator() {
       i = WaitForTokenAndFreeBlock(i);
     }
   }
-  // These checks are not valid if the service has crashed or lost the context.
-  // DCHECK_EQ(blocks_.size(), 1u);
-  // DCHECK_EQ(blocks_[0].state, FREE);
+
+  DCHECK_EQ(blocks_.size(), 1u);
+  DCHECK_EQ(blocks_[0].state, FREE);
 }
 
 // Looks for a non-allocated block that is big enough. Search in the FREE