aura: Make RootWindow::DispatchKeyEvent drop unknown keys.

ui/aura/root_window.cc

 // Copyright (c) 2012 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 "ui/aura/root_window.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 176 matching lines @@
     } else {
       DispatchHeldMouseMove();
     }
   }
   return DispatchMouseEventImpl(event);
 }
 
 bool RootWindow::DispatchKeyEvent(KeyEvent* event) {
   DispatchHeldMouseMove();
   KeyEvent translated_event(*event);
+  if (translated_event.key_code() == ui::VKEY_UNKNOWN)
+    return false;
   return ProcessKeyEvent(focused_window_, &translated_event);
 }
 
 bool RootWindow::DispatchScrollEvent(ScrollEvent* event) {
   DispatchHeldMouseMove();
   event->UpdateForRootTransform(layer()->transform());
 
   last_mouse_location_ = event->location();
   synthesize_mouse_move_ = false;
 
@@ skipping 607 matching lines @@
   // is currently broken. See/ crbug.com/107931.
   MouseEvent event(ui::ET_MOUSE_MOVED,
                    orig_mouse_location,
                    orig_mouse_location,
                    ui::EF_IS_SYNTHESIZED);
   DispatchMouseEvent(&event);
 #endif
 }
 
 }  // namespace aura