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

chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.h

Index: chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.h
diff --git a/chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.h b/chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.h
new file mode 100644
index 0000000000000000000000000000000000000000..30b066b042548f750792b1ac8ef3a6f69f76f43f
--- /dev/null
+++ b/chrome/browser/android/vr_shell/vr_shell_command_buffer_gl.h
@@ -0,0 +1,57 @@
+// 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.
+
+#ifndef CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_COMMAND_BUFFER_GL_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_COMMAND_BUFFER_GL_H_
+
+#include "base/memory/weak_ptr.h"
+#include "gpu/ipc/client/gpu_channel_host.h"
+#include "ui/android/context_provider_factory.h"
+
+namespace gl {
+class SurfaceTexture;
+}
+
+namespace gpu {
+class Mailbox;
+namespace gles2 {
+class GLES2Interface;
+}
+}
+
+namespace ui {
+class ContextProviderCommandBuffer;
+}
+
+namespace vr_shell {
+
+class VrShellCommandBufferGl {
+ public:
+  VrShellCommandBufferGl();
+  ~VrShellCommandBufferGl();
+
+  void CreateContext(scoped_refptr<gl::SurfaceTexture>);
+
+  gpu::gles2::GLES2Interface* GetContext() {
+    return gl_;
+  }
+
+  bool CopyFrameToSurface(int frame_index, const gpu::Mailbox& mailbox,
+                          bool discard);
+
+ private:
+  void OnGpuChannelEstablished(
+      scoped_refptr<gpu::GpuChannelHost> gpu_channel_host,
+      ui::ContextProviderFactory::GpuChannelHostResult result);
+
+  scoped_refptr<ui::ContextProviderCommandBuffer>
+      context_provider_command_buffer_;
+  gpu::gles2::GLES2Interface* gl_ = nullptr;
+  int surface_handle_;
+  base::WeakPtrFactory<VrShellCommandBufferGl> weak_ptr_factory_;
+};
+
+} // namespace vr_shell
+
+#endif // CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_COMMAND_BUFFER_GL_H_