WebVR compositor bypass via BrowserMain context + mailbox

chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.cc

Index: chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.cc b/chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6884641f39df00b82f3b106384ab5ddbc9f9f841
--- /dev/null
+++ b/chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.cc
@@ -0,0 +1,141 @@
+// Copyright 2017 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 "chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.h"
+
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/android/vr_shell/vr_shell_gpu_renderer.h"
+#include "content/public/browser/android/compositor.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+#include "gpu/command_buffer/common/mailbox.h"
+#include "gpu/command_buffer/common/mailbox_holder.h"
+#include "gpu/command_buffer/common/sync_token.h"
+#include "gpu/ipc/client/gpu_channel_host.h"
+#include "gpu/ipc/common/gpu_surface_tracker.h"
+#include "services/ui/public/cpp/gpu/context_provider_command_buffer.h"
+#include "ui/gl/android/surface_texture.h"
+
+#include <android/native_window_jni.h>
+
+namespace vr_shell {
+
+VrShellCommandBufferGl::VrShellCommandBufferGl() : weak_ptr_factory_(this) {}
+
+VrShellCommandBufferGl::~VrShellCommandBufferGl() {
+  if (surface_handle_) {
+    // Unregister from the surface tracker to avoid a resource leak.
+    gpu::GpuSurfaceTracker* tracker = gpu::GpuSurfaceTracker::Get();
+    tracker->UnregisterViewSurface(surface_handle_);
+  }
+}
+
+void VrShellCommandBufferGl::OnGpuChannelEstablished(
+    scoped_refptr<gpu::GpuChannelHost> gpu_channel_host) {
+  // Our attributes must be compatible with the shared offscreen
+  // surface used by virtualized contexts, otherwise mailbox
+  // synchronization doesn't work properly - it assumes a shared
+  // underlying GL context. TODO(klausw): is there a more official
+  // way to get default-compatible settings?
+  gpu::gles2::ContextCreationAttribHelper attributes;
+  attributes.alpha_size = -1;
+  attributes.red_size = 8;
+  attributes.green_size = 8;
+  attributes.blue_size = 8;
+  attributes.stencil_size = 0;
+  attributes.depth_size = 0;
+  attributes.samples = 0;
+  attributes.sample_buffers = 0;
+  attributes.bind_generates_resource = false;
+
+  bool automatic_flushes = false;
+  bool support_locking = false;
+  constexpr ui::ContextProviderCommandBuffer* shared_context_provider = nullptr;
+  context_provider_command_buffer_ =
+      make_scoped_refptr(new ui::ContextProviderCommandBuffer(
+          std::move(gpu_channel_host), gpu::GPU_STREAM_DEFAULT,
+          gpu::GpuStreamPriority::NORMAL, surface_handle_,
+          GURL("chrome://gpu/WebVRContextFactory"), automatic_flushes,
+          support_locking, gpu::SharedMemoryLimits::ForMailboxContext(),
+          attributes, shared_context_provider,
+          ui::command_buffer_metrics::CONTEXT_TYPE_UNKNOWN));
+
+  if (!context_provider_command_buffer_->BindToCurrentThread()) {
+    LOG(ERROR) << __FUNCTION__ << ";;; failed to init ContextProvider";
+    return;
+  }
+
+  gl_ = context_provider_command_buffer_->ContextGL();
+
+  copy_renderer_ = base::MakeUnique<GpuRenderer>(gl_);
+}
+
+std::unique_ptr<gl::ScopedJavaSurface> VrShellCommandBufferGl::CreateSurface(
+    scoped_refptr<gl::SurfaceTexture> surface_texture) {
+  ANativeWindow* window = surface_texture->CreateSurface();
+  gpu::GpuSurfaceTracker* tracker = gpu::GpuSurfaceTracker::Get();
+  ANativeWindow_acquire(window);
+  // Skip ANativeWindow_setBuffersGeometry, the default size appears to work.
+  surface_handle_ = tracker->AddSurfaceForNativeWidget(window);
+
+  auto surface = base::MakeUnique<gl::ScopedJavaSurface>(surface_texture.get());
+  tracker->RegisterViewSurface(surface_handle_, surface->j_surface().obj());
+  // Unregistering happens in the destructor.
+  ANativeWindow_release(window);
+
+  gpu::GpuChannelEstablishFactory* factory =
+      content::Compositor::GetGpuChannelFactory();
+
+  factory->EstablishGpuChannel(
+      base::Bind(&VrShellCommandBufferGl::OnGpuChannelEstablished,
+                 weak_ptr_factory_.GetWeakPtr()));
+
+  return surface;
+}
+
+void VrShellCommandBufferGl::ResizeSurface(int width, int height) {
+  if (!gl_) {
+    LOG(ERROR) << "Cannot resize, not initialized";
+    return;
+  }
+  gl_->ResizeCHROMIUM(width, height, 1.f, false);
+  gl_->Viewport(0, 0, width, height);
+}
+
+bool VrShellCommandBufferGl::CopyFrameToSurface(
+    int frame_index,
+    const gpu::MailboxHolder& mailbox,
+    bool discard) {
+  TRACE_EVENT1("gpu", "VrShellCommandBufferGl::CopyFrameToSurface", "frame",
+               frame_index);
+  if (!gl_) {
+    // We may not have a context yet, i.e. due to surface initialization
+    // being incomplete. This is not an error, but we obviously can't draw
+    // yet.
+    return false;
+  }
+
+  {
+    TRACE_EVENT0("gpu", "VrShellCommandBufferGl::WaitSyncToken");
+    gl_->WaitSyncTokenCHROMIUM(mailbox.sync_token.GetConstData());
+  }
+
+  GLuint vrSourceTexture =
+      gl_->CreateAndConsumeTextureCHROMIUM(GL_TEXTURE_2D, mailbox.mailbox.name);
+
+  if (discard) {
+    // We've consumed the texture, but the caller requested that we
+    // don't draw it because the previous one hasn't been consumed
+    // yet. (Swapping twice on a Surfacewithout consuming one in
+    // between from the SurfaceTexture can lose frames.) This should
+    // be rare, it's a waste of resources and can cause jerky
+    // animation due to the lost frames.
+    return false;
+  } else {
+    copy_renderer_->DrawQuad(gl_, vrSourceTexture);
+    gl_->SwapBuffers();
+    return true;
+  }
+}
+
+}  // namespace vr_shell