Plumb through EGL_NV_post_sub_buffer and GLX_MESA_copy_sub_buffer.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index 12238dad5fd0825eed281e4adc58a48509cf3c14..909ebf52c4584956bf55910f870e87c9963621b0 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -2663,5 +2663,13 @@ void GLES2Implementation::DestroyStreamTextureCHROMIUM(GLuint texture) {
   helper_->DestroyStreamTextureCHROMIUM(texture);
 }
 
+void GLES2Implementation::PostSubBufferCHROMIUM(
+    GLint x, GLint y, GLint width, GLint height) {
+  GPU_CLIENT_LOG("[" << this << "] PostSubBufferCHROMIUM("
+      << x << ", " << y << ", " << width << ", " << height << ")");
+  TRACE_EVENT0("gpu", "GLES2::PostSubBufferCHROMIUM");
+  helper_->PostSubBufferCHROMIUM(x, y, width, height);
+}
+
 }  // namespace gles2
 }  // namespace gpu