Only unbind a Graphics2D on destruction when we're actually bound.

webkit/plugins/ppapi/ppb_graphics_2d_impl.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 WEBKIT_PLUGINS_PPAPI_PPB_GRAPHICS_2D_IMPL_H_
 #define WEBKIT_PLUGINS_PPAPI_PPB_GRAPHICS_2D_IMPL_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 64 matching lines @@
              const gfx::Rect& plugin_rect,
              const gfx::Rect& paint_rect);
 
   // Notifications about the view's progress painting.  See PluginInstance.
   // These messages are used to send Flush callbacks to the plugin.
   void ViewWillInitiatePaint();
   void ViewInitiatedPaint();
   void ViewFlushedPaint();
 
   PPB_ImageData_Impl* image_data() { return image_data_.get(); }
+  PluginInstance* bound_instance() const { return bound_instance_; }
 
   // Scale |op_rect| to logical pixels, taking care to include partially-
   // covered logical pixels (aka DIPs). Also scale optional |delta| to logical
   // pixels as well for scrolling cases. Returns false for scrolling cases where
   // scaling either |op_rect| or |delta| would require scrolling to fall back to
   // invalidation due to rounding errors, true otherwise.
   static bool ConvertToLogicalPixels(float scale,
                                      gfx::Rect* op_rect,
                                      gfx::Point* delta);
 
@@ skipping 117 matching lines @@
   base::WeakPtrFactory<PPB_Graphics2D_Impl> weak_ptr_factory_;
 
   friend class content::PepperGraphics2DHost;
   DISALLOW_COPY_AND_ASSIGN(PPB_Graphics2D_Impl);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PPB_GRAPHICS_2D_IMPL_H_