Update from chromium https://crrev.com/301315

gpu/command_buffer/service/mailbox_manager_impl.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_impl.h"
+
+#include <algorithm>
+
+#include "gpu/command_buffer/service/texture_manager.h"
+
+namespace gpu {
+namespace gles2 {
+
+MailboxManagerImpl::MailboxManagerImpl() {
+}
+
+MailboxManagerImpl::~MailboxManagerImpl() {
+  DCHECK(mailbox_to_textures_.empty());
+  DCHECK(textures_to_mailboxes_.empty());
+}
+
+bool MailboxManagerImpl::UsesSync() {
+  return false;
+}
+
+Texture* MailboxManagerImpl::ConsumeTexture(const Mailbox& mailbox) {
+  MailboxToTextureMap::iterator it =
+      mailbox_to_textures_.find(mailbox);
+  if (it != mailbox_to_textures_.end())
+    return it->second->first;
+
+  return NULL;
+}
+
+void MailboxManagerImpl::ProduceTexture(const Mailbox& mailbox,
+                                        Texture* texture) {
+  MailboxToTextureMap::iterator it = mailbox_to_textures_.find(mailbox);
+  if (it != mailbox_to_textures_.end()) {
+    if (it->second->first == texture)
+      return;
+    TextureToMailboxMap::iterator texture_it = it->second;
+    mailbox_to_textures_.erase(it);
+    textures_to_mailboxes_.erase(texture_it);
+  }
+  InsertTexture(mailbox, texture);
+}
+
+void MailboxManagerImpl::InsertTexture(const Mailbox& mailbox,
+                                       Texture* texture) {
+  texture->SetMailboxManager(this);
+  TextureToMailboxMap::iterator texture_it =
+      textures_to_mailboxes_.insert(std::make_pair(texture, mailbox));
+  mailbox_to_textures_.insert(std::make_pair(mailbox, texture_it));
+  DCHECK_EQ(mailbox_to_textures_.size(), textures_to_mailboxes_.size());
+}
+
+void MailboxManagerImpl::TextureDeleted(Texture* texture) {
+  std::pair<TextureToMailboxMap::iterator,
+            TextureToMailboxMap::iterator> range =
+      textures_to_mailboxes_.equal_range(texture);
+  for (TextureToMailboxMap::iterator it = range.first;
+       it != range.second; ++it) {
+    size_t count = mailbox_to_textures_.erase(it->second);
+    DCHECK(count == 1);
+  }
+  textures_to_mailboxes_.erase(range.first, range.second);
+  DCHECK_EQ(mailbox_to_textures_.size(), textures_to_mailboxes_.size());
+}
+
+}  // namespace gles2
+}  // namespace gpu