Re-land^2 WebVR compositor bypass via BrowserMain context + mailbox

chrome/browser/android/vr_shell/mailbox_to_surface_bridge.cc

Index: chrome/browser/android/vr_shell/mailbox_to_surface_bridge.cc
diff --git a/chrome/browser/android/vr_shell/mailbox_to_surface_bridge.cc b/chrome/browser/android/vr_shell/mailbox_to_surface_bridge.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f8ae07b047a9b3ee35714041079da4a0087258a2
--- /dev/null
+++ b/chrome/browser/android/vr_shell/mailbox_to_surface_bridge.cc
@@ -0,0 +1,319 @@
+// 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/mailbox_to_surface_bridge.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "cc/output/context_provider.h"
+#include "content/public/browser/android/compositor.h"
+#include "gpu/GLES2/gl2extchromium.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>
+
+#define VOID_OFFSET(x) reinterpret_cast<void*>(x)
+#define SHADER(Src) #Src
+
+namespace {
+
+const char* kQuadCopyVertex =
+    SHADER(attribute vec4 a_Position; attribute vec2 a_TexCoordinate;
+           varying vec2 v_TexCoordinate;
+           void main() {
+             v_TexCoordinate = a_TexCoordinate;
+             gl_Position = a_Position;
+           });
+
+const char* kQuadCopyFragment = SHADER(
+    precision highp float; uniform sampler2D u_Texture;
+    varying vec2 v_TexCoordinate;
+    void main() { gl_FragColor = texture2D(u_Texture, v_TexCoordinate); });
+
+static constexpr float kQuadVertices[16] = {
+    //   x     y    u,   v
+    -1.f, 1.f,  0.f, 1.f, -1.f, -1.f, 0.f, 0.f,
+    1.f,  -1.f, 1.f, 0.f, 1.f,  1.f,  1.f, 1.f};
+static constexpr int kQuadVerticesSize = sizeof(float) * 16;
+
+GLuint CompileShader(gpu::gles2::GLES2Interface* gl,
+                     GLenum shaderType,

[piman, 2017/03/08 01:20:37]

nit: here and other places in this file, should be using chromium style
(shader_type, shader_source, shader_handle, etc...)

[klausw, 2017/03/08 02:59:22]

Oops, done. This code had done a round trip through WebKit and its coding
conventions in a previous unsubmitted CL.

+                     const GLchar* shaderSource,
+                     std::string& error) {
+  GLuint shaderHandle = gl->CreateShader(shaderType);
+  if (shaderHandle != 0) {
+    // Pass in the shader source.
+    int len = strlen(shaderSource);
+    gl->ShaderSource(shaderHandle, 1, &shaderSource, &len);
+    // Compile the shader.
+    gl->CompileShader(shaderHandle);
+    // Get the compilation status.
+    GLint status = 0;
+    gl->GetShaderiv(shaderHandle, GL_COMPILE_STATUS, &status);
+    if (status == GL_FALSE) {
+      GLint infoLogLength = 0;
+      gl->GetShaderiv(shaderHandle, GL_INFO_LOG_LENGTH, &infoLogLength);
+      GLchar* strInfoLog = new GLchar[infoLogLength + 1];

[piman, 2017/03/08 01:20:37]

nit: use std::unique_ptr<GLchar[]> instead of explicit delete[]

[klausw, 2017/03/08 02:59:23]

Done.

+      gl->GetShaderInfoLog(shaderHandle, infoLogLength, nullptr, strInfoLog);
+      error = "Error compiling shader: ";
+      error += strInfoLog;
+      delete[] strInfoLog;
+      gl->DeleteShader(shaderHandle);
+      shaderHandle = 0;
+    }
+  }
+
+  return shaderHandle;
+}
+
+GLuint CreateAndLinkProgram(gpu::gles2::GLES2Interface* gl,
+                            GLuint vertextShaderHandle,
+                            GLuint fragmentShaderHandle,
+                            std::string& error) {
+  GLuint programHandle = gl->CreateProgram();
+
+  if (programHandle != 0) {
+    // Bind the vertex shader to the program.
+    gl->AttachShader(programHandle, vertextShaderHandle);
+
+    // Bind the fragment shader to the program.
+    gl->AttachShader(programHandle, fragmentShaderHandle);
+
+    // Link the two shaders together into a program.
+    gl->LinkProgram(programHandle);
+
+    // Get the link status.
+    GLint linkStatus = 0;
+    gl->GetProgramiv(programHandle, GL_LINK_STATUS, &linkStatus);
+
+    // If the link failed, delete the program.
+    if (linkStatus == GL_FALSE) {
+      GLint infoLogLength;
+      gl->GetProgramiv(programHandle, GL_INFO_LOG_LENGTH, &infoLogLength);
+
+      GLchar* strInfoLog = new GLchar[infoLogLength + 1];

[piman, 2017/03/08 01:20:36]

nit: ditto unique_ptr

[klausw, 2017/03/08 02:59:23]

Done.

+      gl->GetProgramInfoLog(programHandle, infoLogLength, nullptr, strInfoLog);
+      error = "Error compiling program: ";
+      error += strInfoLog;
+      delete[] strInfoLog;
+      gl->DeleteProgram(programHandle);
+      programHandle = 0;
+    }
+  }
+
+  return programHandle;
+}
+
+}  // namespace
+
+namespace vr_shell {
+
+MailboxToSurfaceBridge::MailboxToSurfaceBridge() : weak_ptr_factory_(this) {}
+
+MailboxToSurfaceBridge::~MailboxToSurfaceBridge() {
+  if (surface_handle_) {
+    // Unregister from the surface tracker to avoid a resource leak.
+    gpu::GpuSurfaceTracker* tracker = gpu::GpuSurfaceTracker::Get();
+    tracker->UnregisterViewSurface(surface_handle_);
+  }
+}
+
+void MailboxToSurfaceBridge::OnContextAvailable(
+    scoped_refptr<cc::ContextProvider> provider) {
+  // Must save a reference to the ContextProvider to keep it alive,
+  // otherwise the GL context becomes invalid.
+  context_provider_ = provider;
+
+  if (!context_provider_->BindToCurrentThread()) {
+    LOG(ERROR) << "Failed to init ContextProvider";
+    return;
+  }
+
+  gl_ = context_provider_->ContextGL();
+
+  VLOG(1) << __FUNCTION__ << ";;; gl=" << gl_;

[piman, 2017/03/08 01:20:37]

nit: DVLOG

+
+  if (!gl_) {
+    LOG(ERROR) << "Did not get a GL context";

[piman, 2017/03/08 01:20:37]

nit: DLOG ?

[klausw, 2017/03/08 02:59:22]

Done.

+    return;
+  }
+  InitializeRenderer();
+}
+
+void MailboxToSurfaceBridge::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);
+
+  // 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;
+
+  content::Compositor::CreateContextProvider(
+      surface_handle_, attributes, gpu::SharedMemoryLimits::ForMailboxContext(),
+      base::Bind(&MailboxToSurfaceBridge::OnContextAvailable,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void MailboxToSurfaceBridge::ResizeSurface(int width, int height) {
+  if (!gl_) {
+    LOG(ERROR) << "Cannot resize, not initialized";

[piman, 2017/03/08 01:20:37]

nit: DLOG?

[klausw, 2017/03/08 02:59:22]

Moot, I've changed it to save the size for later so that it can resize once the
context has been created, it's no longer treated as an error.

+    return;
+  }
+  gl_->ResizeCHROMIUM(width, height, 1.f, false);
+  gl_->Viewport(0, 0, width, height);
+}
+
+bool MailboxToSurfaceBridge::CopyFrameToSurface(
+    int frame_index,
+    const gpu::MailboxHolder& mailbox,
+    bool discard) {
+  TRACE_EVENT1("gpu", "MailboxToSurfaceBridge::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", "MailboxToSurfaceBridge::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 {
+    DrawQuad(vrSourceTexture);
+    gl_->SwapBuffers();
+    return true;
+  }
+}
+
+void MailboxToSurfaceBridge::InitializeRenderer() {
+  std::string error;
+  GLuint vertexShaderHandle =
+      CompileShader(gl_, GL_VERTEX_SHADER, kQuadCopyVertex, error);
+  CHECK(vertexShaderHandle) << error;

[piman, 2017/03/08 01:20:37]

This should either be a DCHECK, or if the error can happen, should be handled
gracefully.

[klausw, 2017/03/08 02:59:23]

Replaced with this:

  if (!vertex_shader_handle) {
    DestroyContext();
    return;
  }

DestroyContext just nulls gl_ and context_provider_ which suppresses further
attempts to operate on the context, and the failing methods now use DLOG(ERROR)
for diagnostics.

I've confirmed in a debug build that it reports the error and keeps running 
(with blank eye views), and recovers as expected when exiting presentation.

+
+  GLuint fragmentShaderHandle =
+      CompileShader(gl_, GL_FRAGMENT_SHADER, kQuadCopyFragment, error);
+  CHECK(fragmentShaderHandle) << error;

[piman, 2017/03/08 01:20:37]

nit: ditto

[klausw, 2017/03/08 02:59:23]

Done.

+
+  GLuint programHandle = CreateAndLinkProgram(gl_, vertexShaderHandle,
+                                              fragmentShaderHandle, error);
+  CHECK(programHandle) << error;

[piman, 2017/03/08 01:20:37]

nit: ditto

[klausw, 2017/03/08 02:59:23]

Done.

+
+  // Once the program is linked the shader objects are no longer needed
+  gl_->DeleteShader(vertexShaderHandle);
+  gl_->DeleteShader(fragmentShaderHandle);
+
+  GLuint positionHandle = gl_->GetAttribLocation(programHandle, "a_Position");
+  GLuint texCoordHandle =
+      gl_->GetAttribLocation(programHandle, "a_TexCoordinate");
+  GLuint texUniformHandle = gl_->GetUniformLocation(programHandle, "u_Texture");
+
+  GLuint vertexBuffer = 0;
+  gl_->GenBuffers(1, &vertexBuffer);
+  gl_->BindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
+  gl_->BufferData(GL_ARRAY_BUFFER, kQuadVerticesSize, kQuadVertices,
+                  GL_STATIC_DRAW);
+
+  // Set state once only, we assume that nobody else modifies GL state in a way
+  // that would interfere with our operations.
+  gl_->Disable(GL_CULL_FACE);
+  gl_->DepthMask(GL_FALSE);
+  gl_->Disable(GL_DEPTH_TEST);
+  gl_->Disable(GL_SCISSOR_TEST);
+  gl_->Disable(GL_BLEND);
+  gl_->Disable(GL_POLYGON_OFFSET_FILL);
+
+  // Not using gl_->Viewport, we assume that it defaults to the whole
+  // surface and gets updated by ResizeSurface externally as
+  // appropriate.
+
+  gl_->UseProgram(programHandle);
+
+  // Bind vertex attributes
+  gl_->BindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
+
+  gl_->EnableVertexAttribArray(positionHandle);
+  gl_->EnableVertexAttribArray(texCoordHandle);
+
+  static constexpr size_t VERTEX_STRIDE = sizeof(float) * 4;
+  static constexpr size_t POSITION_ELEMENTS = 2;
+  static constexpr size_t TEXCOORD_ELEMENTS = 2;
+  static constexpr size_t POSITION_OFFSET = 0;
+  static constexpr size_t TEXCOORD_OFFSET = sizeof(float) * 2;
+
+  gl_->VertexAttribPointer(positionHandle, POSITION_ELEMENTS, GL_FLOAT, false,
+                           VERTEX_STRIDE, VOID_OFFSET(POSITION_OFFSET));
+  gl_->VertexAttribPointer(texCoordHandle, TEXCOORD_ELEMENTS, GL_FLOAT, false,
+                           VERTEX_STRIDE, VOID_OFFSET(TEXCOORD_OFFSET));
+
+  gl_->ActiveTexture(GL_TEXTURE0);
+  gl_->Uniform1i(texUniformHandle, 0);
+}
+
+void MailboxToSurfaceBridge::DrawQuad(unsigned int textureHandle) {
+  // No need to clear since we're redrawing on top of the entire
+  // viewport, but let the GPU know we don't need the old content
+  // anymore.
+  GLenum discards[] = {GL_COLOR_EXT};
+  gl_->DiscardFramebufferEXT(GL_FRAMEBUFFER, arraysize(discards), discards);
+
+  // Configure texture. This is a 1:1 pixel copy since the surface
+  // size is resized to match the source canvas, so we can use
+  // GL_NEAREST.
+  gl_->BindTexture(GL_TEXTURE_2D, textureHandle);
+  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  gl_->DrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+  gl_->Flush();

[piman, 2017/03/08 01:20:37]

nit: this may be unnecessary / redundant with the SwapBuffers that follows the
DrawQuad in CopyFrameToSurface (SwapBuffers implicitly flushes).

[klausw, 2017/03/08 02:59:22]

Removed.

+}
+
+}  // namespace vr_shell