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

chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h

Index: chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h
diff --git a/chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h b/chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h
new file mode 100644
index 0000000000000000000000000000000000000000..8ba1540a127eb590311680e157f2527fa9e7ab11
--- /dev/null
+++ b/chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h
@@ -0,0 +1,63 @@
+// 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_MAILBOX_TO_SURFACE_BRIDGE_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_MAILBOX_TO_SURFACE_BRIDGE_H_
+
+#include "base/memory/weak_ptr.h"
+
+namespace gl {
+class SurfaceTexture;
+}
+
+namespace gpu {
+struct MailboxHolder;
+namespace gles2 {
+class GLES2Interface;
+}
+}
+
+namespace cc {
+class ContextProvider;
+}
+
+namespace vr_shell {
+
+class MailboxToSurfaceBridge {
+ public:
+  MailboxToSurfaceBridge();
+  ~MailboxToSurfaceBridge();
+
+  void CreateSurface(gl::SurfaceTexture*);
+
+  void ResizeSurface(int width, int height);
+
+  // Returns true if swapped successfully. This can fail if the GL
+  // context isn't ready for use yet, in that case the caller
+  // won't get a new frame on the SurfaceTexture.
+  bool CopyMailboxToSurfaceAndSwap(const gpu::MailboxHolder& mailbox);
+
+ private:
+  void OnContextAvailable(scoped_refptr<cc::ContextProvider>);
+  void InitializeRenderer();
+  void DestroyContext();
+  void DrawQuad(unsigned int textureHandle);
+
+  scoped_refptr<cc::ContextProvider> context_provider_;
+  gpu::gles2::GLES2Interface* gl_ = nullptr;
+  int surface_handle_ = 0;
+
+  // Saved state for a pending resize, the dimensions are only
+  // valid if needs_resize_ is true.
+  bool needs_resize_ = false;
+  int resize_width_;
+  int resize_height_;
+
+  // Must be last.
+  base::WeakPtrFactory<MailboxToSurfaceBridge> weak_ptr_factory_;
+};
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_MAILBOX_TO_SURFACE_BRIDGE_H_