Make lost context callback a base::Closure thru the WGC3DProvider.

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 193 matching lines @@
 WebGraphicsContext3D* DrawingBuffer::context()
 {
     return m_context;
 }
 
 gpu::gles2::GLES2Interface* DrawingBuffer::contextGL()
 {
     return m_gl;
 }
 
+WebGraphicsContext3DProvider* DrawingBuffer::contextProvider()
+{
+    return m_contextProvider.get();
+}
+
 void DrawingBuffer::setIsHidden(bool hidden)
 {
     if (m_isHidden == hidden)
         return;
     m_isHidden = hidden;
     if (m_isHidden)
         freeRecycledMailboxes();
 }
 
 void DrawingBuffer::setFilterQuality(SkFilterQuality filterQuality)
@@ skipping 802 matching lines @@
 
     if (m_antiAliasingMode == MSAAImplicitResolve)
         m_gl->FramebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target, m_colorBuffer.textureId, 0, m_sampleCount);
     else
         m_gl->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target, m_colorBuffer.textureId, 0);
 
     m_gl->BindTexture(GL_TEXTURE_2D, m_texture2DBinding);
 }
 
 } // namespace blink