Draw the offscreen texture to reflector's surface without extra copy

content/browser/compositor/reflector_texture.cc

+// Copyright 2015 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 "content/browser/compositor/reflector_texture.h"
+
+#include "content/browser/compositor/owned_mailbox.h"
+#include "content/common/gpu/client/context_provider_command_buffer.h"
+#include "content/common/gpu/client/gl_helper.h"
+#include "gpu/command_buffer/client/context_support.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+
+namespace content {
+
+ReflectorTexture::ReflectorTexture(cc::ContextProvider* context_provider)
+    : texture_id_(0) {
+  GLHelper* shared_helper =
+      ImageTransportFactory::GetInstance()->GetGLHelper();
+  mailbox_ = new OwnedMailbox(shared_helper);
+  gpu::gles2::GLES2Interface* gl = context_provider->ContextGL();
+
+  gl_helper_.reset(new GLHelper(gl, context_provider->ContextSupport()));
+
+  texture_id_ = gl_helper_->ConsumeMailboxToTexture(
+      mailbox_->mailbox(), mailbox_->sync_point());
+}
+
+ReflectorTexture::~ReflectorTexture() {
+  gl_helper_->DeleteTexture(texture_id_);
+}
+
+void ReflectorTexture::CopyTextureFullImage(const gfx::Size& size) {
+  gl_helper_->CopyTextureFullImage(texture_id_, size);
+  // Insert a barrier to make the copy show up in the mirroring compositor's
+  // mailbox. Since the the compositor contexts and the
+  // ImageTransportFactory's
+  // GLHelper are all on the same GPU channel, this is sufficient instead of
+  // plumbing through a sync point.
+  gl_helper_->InsertOrderingBarrier();
+}
+
+void ReflectorTexture::CopyTextureSubImage(const gfx::Rect& rect) {
+  gl_helper_->CopyTextureSubImage(texture_id_, rect);
+  // Insert a barrier for the same reason above.
+  gl_helper_->InsertOrderingBarrier();
+}
+
+}  // namespace content