Clean up event flags a bit:

components/exo/keyboard.cc

Index: components/exo/keyboard.cc
diff --git a/components/exo/keyboard.cc b/components/exo/keyboard.cc
index 4a7c5c37705dd4f6569a9bb4fe5384a9fac5d449..8e307955c72998370241f903555f4276cdf1dd6f 100644
--- a/components/exo/keyboard.cc
+++ b/components/exo/keyboard.cc
@@ -36,10 +36,10 @@ Keyboard::~Keyboard() {
 // ui::EventHandler overrides:
 
 void Keyboard::OnKeyEvent(ui::KeyEvent* event) {
-  const int kModifierMask = ui::EF_CAPS_LOCK_DOWN | ui::EF_SHIFT_DOWN |
-                            ui::EF_CONTROL_DOWN | ui::EF_ALT_DOWN |
-                            ui::EF_COMMAND_DOWN | ui::EF_ALTGR_DOWN |
-                            ui::EF_MOD3_DOWN | ui::EF_NUM_LOCK_DOWN;
+  const int kModifierMask =
+      ui::EF_SHIFT_DOWN | ui::EF_CONTROL_DOWN | ui::EF_ALT_DOWN |
+      ui::EF_COMMAND_DOWN | ui::EF_ALTGR_DOWN | ui::EF_MOD3_DOWN |
+      ui::EF_NUM_LOCK_ON | ui::EF_CAPS_LOCK_ON | ui::EF_SCROLL_LOCK_ON;

[reveman, 2016/01/07 12:02:59]

nit: please avoid adding ui::EF_SCROLL_LOCK_ON as part of this patch as it
requires additional changes to the wayland code to avoid sending unnecessary
modifier events. ie. if scroll lock state changes then we'll send modifier
events to wayland clients without any modifiers that the client is aware of
actually changing.

[Peter Kasting, 2016/01/07 12:15:24]

Oh, I thought you had told me this would have no effect.  Sure, I'll remove it
from this change then.

Do you want me to write a separate change for this, or do something else?

[reveman, 2016/01/07 12:32:36]

Sorry, I failed to think of this before. It wouldn't break anything but it would
have a subtle change in behavior which I think is best to avoid as part of this
patch.
It would be more correct to move this into the wayland code (ie. move this
modifider mask to the KeyboardDelegate) but I think we can just leave this as is
for now.

   int modifier_flags = event->flags() & kModifierMask;
   if (modifier_flags != modifier_flags_) {
     modifier_flags_ = modifier_flags;