gpu: Add YCbCr 420v extension.

ui/gl/gl_image_io_surface.h

Index: ui/gl/gl_image_io_surface.h
diff --git a/ui/gl/gl_image_io_surface.h b/ui/gl/gl_image_io_surface.h
index 186f5a972e14bfa9c85a523ebbf61fa2eee197d8..623ad21b6b76f6766f5f5a2e0a50be45c987cb6f 100644
--- a/ui/gl/gl_image_io_surface.h
+++ b/ui/gl/gl_image_io_surface.h
@@ -53,6 +53,8 @@ class GL_EXPORT GLImageIOSurface : public GLImage {
 
   static void SetLayerForWidget(gfx::AcceleratedWidget widget, CALayer* layer);
 
+  static unsigned GetInternalFormatForTesting(gfx::BufferFormat format);
+
  protected:
   ~GLImageIOSurface() override;
 
@@ -64,6 +66,15 @@ class GL_EXPORT GLImageIOSurface : public GLImage {
   gfx::GenericSharedMemoryId io_surface_id_;
   base::ThreadChecker thread_checker_;
 
+  // GL state to support 420v IOSurface conversion to RGB.
+  unsigned framebuffer_ = 0;
+  unsigned vertex_shader_ = 0;
+  unsigned fragment_shader_ = 0;
+  unsigned program_ = 0;
+  int size_location_ = -1;
+  unsigned vertex_buffer_ = 0;
+  unsigned yuv_textures_[2] = {};
+
   DISALLOW_COPY_AND_ASSIGN(GLImageIOSurface);
 };