gestures: add a dummy member for empty structure.

In C, empty struct has size 0, in C++, it has size 1.
Clang 3.5 catches this as a warning.

BUG=chromium:341155
TEST=emerge-lumpy gestures, the warning is gone.

Change-Id: Ib46e974ac2e499f9277c43e1c96e0689cbf71ba1
Reviewed-on: https://chromium-review.googlesource.com/185042
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
1 file changed