Add more out of line copy ctors for complex classes.

mojo/edk/system/request_context.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_EDK_SYSTEM_REQUEST_CONTEXT_H_
 #define MOJO_EDK_SYSTEM_REQUEST_CONTEXT_H_
 
 #include "base/containers/stack_container.h"
 #include "base/macros.h"
 #include "mojo/edk/system/handle_signals_state.h"
@@ skipping 49 matching lines @@
   void AddWatchCancelFinalizer(scoped_refptr<Watcher> watcher);
 
  private:
   // Is this request context the current one?
   bool IsCurrent() const;
 
   struct WatchNotifyFinalizer {
     WatchNotifyFinalizer(scoped_refptr<Watcher> watcher,
                          MojoResult result,
                          const HandleSignalsState& state);
+    WatchNotifyFinalizer(const WatchNotifyFinalizer& other);
     ~WatchNotifyFinalizer();
 
     scoped_refptr<Watcher> watcher;
     MojoResult result;
     HandleSignalsState state;
   };
 
   // Chosen by fair dice roll.
   //
   // TODO: We should measure the distribution of # of finalizers typical to
@@ skipping 16 matching lines @@
   // the rest of this class and its usages.
   base::ThreadLocalPointer<RequestContext>* tls_context_;
 
   DISALLOW_COPY_AND_ASSIGN(RequestContext);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_REQUEST_CONTEXT_H_