Clean up event flags a bit:

components/exo/keyboard.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/exo/keyboard.h"
 
 #include "ash/shell.h"
 #include "components/exo/keyboard_delegate.h"
 #include "components/exo/surface.h"
 #include "ui/aura/client/focus_client.h"
@@ skipping 18 matching lines @@
     focus_->RemoveSurfaceObserver(this);
   aura::client::GetFocusClient(ash::Shell::GetPrimaryRootWindow())
       ->RemoveObserver(this);
   ash::Shell::GetInstance()->RemovePreTargetHandler(this);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // 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;
+  // These modifiers reflect what Wayland is aware of.  For example,
+  // EF_SCROLL_LOCK_ON is missing because Wayland doesn't support scroll lock.
+  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;
   int modifier_flags = event->flags() & kModifierMask;
   if (modifier_flags != modifier_flags_) {
     modifier_flags_ = modifier_flags;
     if (focus_)
       delegate_->OnKeyboardModifiers(modifier_flags_);
   }
 
   switch (event->type()) {
     case ui::ET_KEY_PRESSED: {
       auto it =
@@ skipping 57 matching lines @@
 
 Surface* Keyboard::GetEffectiveFocus(aura::Window* window) const {
   Surface* focus = Surface::AsSurface(window);
   if (!focus)
     return nullptr;
 
   return delegate_->CanAcceptKeyboardEventsForSurface(focus) ? focus : nullptr;
 }
 
 }  // namespace exo