Workaround to prevent crashes when destroying CGL contexts

content/browser/compositor/io_surface_layer_mac.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 CONTENT_BROWSER_COMPOSITOR_IO_SURFACE_LAYER_MAC_H_
 #define CONTENT_BROWSER_COMPOSITOR_IO_SURFACE_LAYER_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 #include <IOSurface/IOSurfaceAPI.h>
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/ref_counted.h"
 #include "base/timer/timer.h"
 #include "ui/gfx/size.h"
+#include "ui/gl/scoped_cgl.h"
 
 @class IOSurfaceLayer;
 
 namespace content {
 class IOSurfaceLayerHelper;
 
 // The interface through which the IOSurfaceLayer calls back into
 // the structrue that created it (RenderWidgetHostViewMac or
 // BrowserCompositorViewMac).
 class IOSurfaceLayerClient {
@@ skipping 34 matching lines @@
   // Set when inside a BeginPumpingFrames/EndPumpingFrames block.
   bool is_pumping_frames_;
 
   // The IOSurface being drawn by this layer.
   base::ScopedCFTypeRef<IOSurfaceRef> io_surface_;
 
   // The size of the frame in pixels. This will be less or equal than the pixel
   // size of |io_surface_|.
   gfx::Size frame_pixel_size_;
 
-  // The GL texture that is bound to |io_surface_|. If |io_surface_| changes,
-  // then this is marked as dirty by setting |io_surface_texture_dirty_|.
+  // The GL texture that was bound to |io_surface_| during the last draw call,
+  // along with the context that was done in, and the value of |io_surface_| at
+  // the time of the bind.
   GLuint io_surface_texture_;
-  bool io_surface_texture_dirty_;
+  base::ScopedTypeRef<CGLContextObj> io_surface_texture_context_;
+  base::ScopedCFTypeRef<IOSurfaceRef> io_surface_texture_io_surface_;
 
   // The CGL renderer ID, captured at draw time.
   GLint cgl_renderer_id_;
 }
 
 - (id)initWithClient:(content::IOSurfaceLayerClient*)client
      withScaleFactor:(float)scale_factor;
 
 // Called when a new frame is received.
 - (void)gotFrameWithIOSurface:(IOSurfaceID)io_surface_id
@@ skipping 13 matching lines @@
 // displayed frame).
 - (void)setNeedsDisplayAndDisplayAndAck;
 
 // Mark a bracket in which new frames are being pumped in a restricted nested
 // run loop.
 - (void)beginPumpingFrames;
 - (void)endPumpingFrames;
 @end
 
 #endif  // CONTENT_BROWSER_COMPOSITOR_IO_SURFACE_LAYER_MAC_H_