X11: Fix msan use-of-uninitialized-value error

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index c64b0ca1434a66d1260d1b637c5175c3cb781935..513db167c3cb7ebf08434998735971a6eb864b87 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -1679,6 +1679,7 @@ void DesktopWindowTreeHostX11::UpdateMinAndMaxSize() {
   max_size_in_pixels_ = maximum_in_pixels;
 
   XSizeHints hints;

[Nico, 2017/03/11 00:40:44]

= {} here to zero out all the fields doesn't work?

[Tom (Use chromium acct), 2017/03/11 00:45:35]

That would work too, but it's unnecessary because Xlib only reads fields in
XSizeHints if the appropriate bit is set in |flags|.

Having it this way ensures that msan errors will be detected in the case of
setting a big in |flags|, and forgetting to set the corresponding field.

+  hints.flags = 0;
   long supplied_return;
   XGetWMNormalHints(xdisplay_, xwindow_, &hints, &supplied_return);