gpu: Add out-of-line copy ctors for complex classes.

gpu/command_buffer/service/mailbox_manager_sync.cc

 // Copyright 2014 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.
 
 #include "gpu/command_buffer/service/mailbox_manager_sync.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <queue>
@@ skipping 148 matching lines @@
       return it->second;
   }
   return NULL;
 }
 
 MailboxManagerSync::TextureGroupRef::TextureGroupRef(unsigned version,
                                                      TextureGroup* group)
     : version(version), group(group) {
 }
 
+MailboxManagerSync::TextureGroupRef::TextureGroupRef(
+    const TextureGroupRef& other) = default;
+
 MailboxManagerSync::TextureGroupRef::~TextureGroupRef() {
 }
 
 MailboxManagerSync::MailboxManagerSync() {
 }
 
 MailboxManagerSync::~MailboxManagerSync() {
   DCHECK_EQ(0U, texture_to_group_.size());
 }
 
@@ skipping 152 matching lines @@
 
   if (!needs_update.empty()) {
     for (const TextureUpdatePair& pair : needs_update) {
       pair.second.UpdateTexture(pair.first);
     }
   }
 }
 
 }  // namespace gles2
 }  // namespace gpu