Only overwrite DomKey of keydown event if it's a printable character

ui/base/ime/input_method_win.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/base/ime/input_method_win.h"
 
 #include <stddef.h>
 #include <stdint.h>
+#include <cwctype>
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
 #include "ui/base/ime/ime_bridge.h"
 #include "ui/base/ime/ime_engine_handler_interface.h"
 #include "ui/base/ime/text_input_client.h"
 #include "ui/base/ime/win/tsf_input_scope.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/events/event.h"
 #include "ui/events/event_constants.h"
@@ skipping 140 matching lines @@
     } else if (key.type() == ui::ET_KEY_RELEASED &&
                (code == ui::VKEY_SHIFT || code == ui::VKEY_CONTROL) &&
                pending_requested_direction_ != base::i18n::UNKNOWN_DIRECTION) {
       GetTextInputClient()->ChangeTextDirectionAndLayoutAlignment(
           pending_requested_direction_);
       pending_requested_direction_ = base::i18n::UNKNOWN_DIRECTION;
     }
   }
 
   // If only 1 WM_CHAR per the key event, set it as the character of it.
-  if (char_msgs.size() == 1)
+  if (char_msgs.size() == 1 &&
+      !std::iswcntrl(static_cast<wint_t>(char_msgs[0].wParam)))
     event->set_character(static_cast<base::char16>(char_msgs[0].wParam));
 
   // Dispatches the key events to the Chrome IME extension which is listening to
   // key events on the following two situations:
   // 1) |char_msgs| is empty when the event is non-character key.
   // 2) |char_msgs|.size() == 1 when the event is character key and the WM_CHAR
   // messages have been combined in the event processing flow.
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableMergeKeyCharEvents) &&
       char_msgs.size() <= 1 && GetEngine() &&
@@ skipping 518 matching lines @@
   ui::IMEEngineHandlerInterface* engine = GetEngine();
   if (engine) {
     if (old_text_input_type != ui::TEXT_INPUT_TYPE_NONE)
       engine->FocusOut();
     if (GetTextInputType() != ui::TEXT_INPUT_TYPE_NONE)
       engine->FocusIn(context);
   }
 }
 
 }  // namespace ui