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

content/browser/compositor/io_surface_texture_mac.h

Index: content/browser/compositor/io_surface_texture_mac.h
diff --git a/content/browser/compositor/io_surface_texture_mac.h b/content/browser/compositor/io_surface_texture_mac.h
index b514c56ea155ad3e1be1d139568dc389c973bd96..b44a4b4750dd6688210508eb20f9f3e9a9b9f9e5 100644
--- a/content/browser/compositor/io_surface_texture_mac.h
+++ b/content/browser/compositor/io_surface_texture_mac.h
@@ -58,8 +58,9 @@
   // 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>;
@@ -79,7 +80,7 @@
   // 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_;