Pepper takes ownership of a mailbox before passing it to the texture layer.

cc/layers/texture_layer.cc

 // Copyright 2010 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 "cc/layers/texture_layer.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/memory/ptr_util.h"
@@ skipping 136 matching lines @@
 
 void TextureLayer::SetTextureMailbox(
     const TextureMailbox& mailbox,
     std::unique_ptr<SingleReleaseCallback> release_callback) {
   bool requires_commit = true;
   bool allow_mailbox_reuse = false;
   SetTextureMailboxInternal(mailbox, std::move(release_callback),
                             requires_commit, allow_mailbox_reuse);
 }
 
-static void IgnoreReleaseCallback(const gpu::SyncToken& sync_token, bool lost) {

[ccameron, 2016/04/22 18:25:54]

:D

-}
-
-void TextureLayer::SetTextureMailboxWithoutReleaseCallback(
-    const TextureMailbox& mailbox) {
-  // We allow reuse of the mailbox if there is a new sync point signalling new
-  // content, and the release callback goes nowhere since we'll be calling it
-  // multiple times for the same mailbox.
-  DCHECK(!mailbox.IsValid() || !holder_ref_ ||
-         !mailbox.Equals(holder_ref_->holder()->mailbox()) ||
-         mailbox.sync_token() != holder_ref_->holder()->mailbox().sync_token());
-  std::unique_ptr<SingleReleaseCallback> release;
-  bool requires_commit = true;
-  bool allow_mailbox_reuse = true;
-  if (mailbox.IsValid())
-    release = SingleReleaseCallback::Create(base::Bind(&IgnoreReleaseCallback));
-  SetTextureMailboxInternal(mailbox, std::move(release), requires_commit,
-                            allow_mailbox_reuse);
-}
-
 void TextureLayer::SetNeedsDisplayRect(const gfx::Rect& dirty_rect) {
   Layer::SetNeedsDisplayRect(dirty_rect);
 }
 
 void TextureLayer::SetLayerTreeHost(LayerTreeHost* host) {
   if (layer_tree_host() == host) {
     Layer::SetLayerTreeHost(host);
     return;
   }
 
@@ skipping 129 matching lines @@
 void TextureLayer::TextureMailboxHolder::ReturnAndReleaseOnImplThread(
     const gpu::SyncToken& sync_token,
     bool is_lost,
     BlockingTaskRunner* main_thread_task_runner) {
   Return(sync_token, is_lost);
   main_thread_task_runner->PostTask(
       FROM_HERE, base::Bind(&TextureMailboxHolder::InternalRelease, this));
 }
 
 }  // namespace cc