Fix swapbuffers callback crash

chrome/renderer/webgraphicscontext3d_command_buffer_impl.cc

 // Copyright (c) 2010 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.
 
 #if defined(ENABLE_GPU)
 
 #include "chrome/renderer/webgraphicscontext3d_command_buffer_impl.h"
 
 #include <GLES2/gl2.h>
 #ifndef GL_GLEXT_PROTOTYPES
@@ skipping 101 matching lines @@
     web_view_ = web_view;
     context_ = ggl::CreateViewContext(
         host,
         view_id,
         renderview->routing_id(),
         kWebGraphicsContext3DPerferredGLExtensions,
         attribs);
     if (context_) {
       ggl::SetSwapBuffersCallback(
           context_,
-          NewCallback(renderview, &RenderView::DidFlushPaint));
+          NewCallback(this,
+                      &WebGraphicsContext3DCommandBufferImpl::OnSwapBuffers));
     }
   } else {
     bool compositing_enabled = !CommandLine::ForCurrentProcess()->HasSwitch(
         switches::kDisableAcceleratedCompositing);
     ggl::Context* parent_context = NULL;
     // If GPU compositing is enabled we need to create a GL context that shares
     // resources with the compositor's context.
     if (compositing_enabled) {
       // Asking for the WebGraphicsContext3D on the WebView will force one to
       // be created if it doesn't already exist. When the compositor is created
@@ skipping 893 matching lines @@
   glDeleteTextures(1, &texture);
 }
 
 void WebGraphicsContext3DCommandBufferImpl::copyTextureToCompositor(
     unsigned texture, unsigned parentTexture) {
   makeContextCurrent();
   glCopyTextureToParentTextureCHROMIUM(texture, parentTexture);
   glFlush();
 }
 
+void WebGraphicsContext3DCommandBufferImpl::OnSwapBuffers() {
+  // This may be called after tear-down of the RenderView.
+  RenderView* renderview =
+      web_view_ ? RenderView::FromWebView(web_view_) : NULL;
+  if (renderview)
+    renderview->DidFlushPaint();
+}
+
 #endif  // defined(ENABLE_GPU)