Take a screenshot in maximize mode when volume down and power are pressed.

ash/wm/maximize_mode/maximize_mode_event_blocker.cc

 // Copyright 2014 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 "ash/wm/maximize_mode/maximize_mode_event_blocker.h"
 
 #include "ash/shell.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/aura/client/cursor_client.h"
 #include "ui/events/event_targeter.h"
@@ skipping 45 matching lines @@
     ui::EventTarget* root,
     ui::Event* event) {
   if (event->HasNativeEvent()) {
     if (event->IsMouseEvent())
       return NULL;
     if (event->IsKeyEvent()) {
       // TODO(bruthig): Fix this to block rewritten volume keys
       // (i.e. F9 and F10)  from the device's keyboard. https://crbug.com/368669
       ui::KeyEvent* key_event = static_cast<ui::KeyEvent*>(event);
       if (key_event->key_code() != ui::VKEY_VOLUME_DOWN &&
-          key_event->key_code() != ui::VKEY_VOLUME_UP) {
+          key_event->key_code() != ui::VKEY_VOLUME_UP
+#if defined(OS_CHROMEOS)
+          && key_event->key_code() != ui::VKEY_POWER
+#endif
+          ) {
         return NULL;
       }
     }
   }
   return default_targeter_->FindTargetForEvent(root, event);
 }
 
 }  // namespace
 
 MaximizeModeEventBlocker::MaximizeModeEventBlocker() {
@@ skipping 26 matching lines @@
     aura::Window* root_window) {
   BlockKeyboardAndTouchpadTargeter* targeter =
       new BlockKeyboardAndTouchpadTargeter();
   aura::ScopedWindowTargeter* scoped_targeter = new aura::ScopedWindowTargeter(
       root_window, scoped_ptr<ui::EventTargeter>(targeter));
   targeter->SetDefaultTargeter(scoped_targeter->old_targeter());
   targeters_.push_back(scoped_targeter);
 }
 
 }  // namespace ash