Plumb through EGL_NV_post_sub_buffer and GLX_MESA_copy_sub_buffer.

webkit/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc

Index: webkit/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc
diff --git a/webkit/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc b/webkit/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc
index 71a8a70122cf91a567c50c580cbd3c33f4c80bb0..4f8044b5d0144d2f2e45a86bd51f759da9eac612 100644
--- a/webkit/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc
+++ b/webkit/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc
@@ -758,6 +758,11 @@ void WebGraphicsContext3DInProcessCommandBufferImpl::prepareTexture() {
   context_->SwapBuffers();
 }
 
+void WebGraphicsContext3DInProcessCommandBufferImpl::postSubBufferCHROMIUM(
+    int x, int y, int width, int height) {
+  gl_->PostSubBufferCHROMIUM(x, y, width, height);
+}
+
 void WebGraphicsContext3DInProcessCommandBufferImpl::reshape(
     int width, int height) {
   cached_width_ = width;