WebGL: GL_RGB emulation for IOSurface backed textures. [For reference only]

ui/gl/gl_image_io_surface.h

 // Copyright 2013 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 UI_GL_GL_IMAGE_IO_SURFACE_H_
 #define UI_GL_GL_IMAGE_IO_SURFACE_H_
 
 #include <IOSurface/IOSurface.h>
 #include <stdint.h>
 
@@ skipping 31 matching lines @@
                        const gfx::Point& offset,
                        const gfx::Rect& rect) override;
   bool ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                             int z_order,
                             gfx::OverlayTransform transform,
                             const gfx::Rect& bounds_rect,
                             const gfx::RectF& crop_rect) override;
   void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd,
                     uint64_t process_tracing_id,
                     const std::string& dump_name) override;
+  bool EmulatingRGB() const override;
 
   gfx::GenericSharedMemoryId io_surface_id() const { return io_surface_id_; }
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface();
 
   static void SetLayerForWidget(gfx::AcceleratedWidget widget, CALayer* layer);
 
   static unsigned GetInternalFormatForTesting(gfx::BufferFormat format);
 
  protected:
   ~GLImageIOSurface() override;
 
  private:
   const gfx::Size size_;
-  const unsigned internalformat_;
+  unsigned internalformat_;
+
+  // This class is capable of emulating RGB internal format with RGBA
+  // internal format. The member |internalformat_| holds the format
+  // exposed to the command buffer. |desired_internalformat_| holds the format
+  // desired by the caller of the constructor of this object.
+  const unsigned desired_internalformat_;
   gfx::BufferFormat format_;
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
   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);
 };
 
 }  // namespace gl
 
 #endif  // UI_GL_GL_IMAGE_IO_SURFACE_H_