Fix the bug that closing a tab which owns a fullscreen Flash widget causes crash.

content/renderer/render_widget_fullscreen_pepper.h

 // Copyright (c) 2011 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_RENDERER_RENDER_WIDGET_FULLSCREEN_PEPPER_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_FULLSCREEN_PEPPER_H_
 
 #include "base/task.h"
 #include "content/renderer/render_widget_fullscreen.h"
 #include "content/renderer/gpu/renderer_gl_context.h"
@@ skipping 23 matching lines @@
   virtual void Invalidate();
   virtual void InvalidateRect(const WebKit::WebRect& rect);
   virtual void ScrollRect(int dx, int dy, const WebKit::WebRect& rect);
   virtual void Destroy();
   virtual void DidChangeCursor(const WebKit::WebCursorInfo& cursor);
   virtual webkit::ppapi::PluginDelegate::PlatformContext3D* CreateContext3D();
 
   RendererGLContext* context() const { return context_; }
   void SwapBuffers();
 
+  // Could be NULL when this widget is closing.
+  webkit::ppapi::PluginInstance* plugin() const { return plugin_; }
+
  protected:
   RenderWidgetFullscreenPepper(webkit::ppapi::PluginInstance* plugin,
                                const GURL& active_url);
   virtual ~RenderWidgetFullscreenPepper();
 
   // RenderWidget API.
   virtual void DidInitiatePaint();
   virtual void DidFlushPaint();
   virtual void Close();
   virtual webkit::ppapi::PluginInstance* GetBitmapForOptimizedPluginPaint(
@@ skipping 38 matching lines @@
   RendererGLContext* context_;
   unsigned int buffer_;
   unsigned int program_;
 
   ScopedRunnableMethodFactory<RenderWidgetFullscreenPepper> method_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetFullscreenPepper);
 };
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_FULLSCREEN_PEPPER_H_