Revert of Use a single CGLContextObj to draw and update the IOSurface

content/browser/compositor/io_surface_texture_mac.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_COMPOSITOR_IO_SURFACE_TEXTURE_MAC_H_
 #define CONTENT_BROWSER_COMPOSITOR_IO_SURFACE_TEXTURE_MAC_H_
 
 #include <deque>
 #include <list>
 #include <vector>
@@ skipping 40 matching lines @@
   bool SetIOSurface(
       IOSurfaceID io_surface_id,
       const gfx::Size& pixel_size) WARN_UNUSED_RESULT;
 
   // Blit the IOSurface to the rectangle specified by |window_rect| in DIPs,
   // with the origin in the lower left corner. If the window rect's size is
   // larger than the IOSurface, the remaining right and bottom edges will be
   // white. |window_scale_factor| is 1 in normal views, 2 in HiDPI views.
   bool DrawIOSurface() WARN_UNUSED_RESULT;
 
-  // Returns the GL context in which this texture was created.
-  scoped_refptr<IOSurfaceContext> context() const { return context_; }
+  // Returns true if the offscreen context used by this surface has been
+  // poisoned.
+  bool HasBeenPoisoned() const;
 
  private:
   friend class base::RefCounted<IOSurfaceTexture>;
 
   IOSurfaceTexture(
       const scoped_refptr<IOSurfaceContext>& context);
   ~IOSurfaceTexture();
 
   // Unref the IOSurfaceTexture and delete the associated GL texture. If the GPU
   // process is no longer referencing it, this will delete the IOSurface.
   void ReleaseIOSurfaceAndTexture();
 
   // Check for GL errors and store the result in error_. Only return new
   // errors
   GLenum GetAndSaveGLError();
 
   // Offscreen context used for all operations other than drawing to the
   // screen. This is in the same share group as the contexts used for
   // drawing, and is the same for all IOSurfaces in all windows.
-  scoped_refptr<IOSurfaceContext> context_;
+  scoped_refptr<IOSurfaceContext> offscreen_context_;
 
   // The IOSurface and its non-rounded size.
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
   gfx::Size pixel_size_;
 
   // The "live" OpenGL texture referring to this IOSurfaceRef. Note
   // that per the CGLTexImageIOSurface2D API we do not need to
   // explicitly update this texture's contents once created. All we
   // need to do is ensure it is re-bound before attempting to draw
   // with it.
@@ skipping 19 matching lines @@
 
   static void EvictionScheduleDoEvict();
   static void EvictionDoEvict();
   static base::LazyInstance<EvictionQueue> eviction_queue_;
   static bool eviction_scheduled_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_COMPOSITOR_IO_SURFACE_TEXTURE_MAC_H_