Make sure buffers are large enough to hold the Result structure.

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index d3836079cebdf723044eb62e96246b1e6ee2e27e..479b2d6be187cde9f2c8555557e3138153ef5373 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -6703,7 +6703,7 @@ class GETnHandler(TypeHandler):
   typedef cmds::%(func_name)s::Result Result;
   Result* result = GetSharedMemoryAndSizeAs<Result*>(
       c.%(last_arg_name)s_shm_id, c.%(last_arg_name)s_shm_offset,
-      &buffer_size);
+      sizeof(Result), &buffer_size);
   %(last_arg_type)s %(last_arg_name)s = result ? result->GetData() : NULL;
   if (%(last_arg_name)s == NULL) {
     return error::kOutOfBounds;