Make backspace not go back while IME is active.

chrome/common/native_web_keyboard_event.h

 // Copyright (c) 2009 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.
 
 #ifndef CHROME_COMMON_NATIVE_WEB_KEYBOARD_EVENT_H_
 #define CHROME_COMMON_NATIVE_WEB_KEYBOARD_EVENT_H_
 
 #include "base/basictypes.h"
 #include "webkit/api/public/WebInputEvent.h"
 
@@ skipping 30 matching lines @@
 
   NativeWebKeyboardEvent(const NativeWebKeyboardEvent& event);
   ~NativeWebKeyboardEvent();
 
   NativeWebKeyboardEvent& operator=(const NativeWebKeyboardEvent& event);
 
 #if defined(OS_WIN)
   MSG os_event;
 #elif defined(OS_MACOSX)
   NSEvent* os_event;
+
+  // True if the browser should ignore this event if it's not handled by the
+  // renderer. This happens for RawKeyDown events that are created while IME is
+  // active and is necessary to prevent backspace from doing "history back" if
+  // it is hit in ime mode.
+  bool skip_in_browser;
 #elif defined(OS_LINUX)
   GdkEventKey* os_event;
 #endif
 };
 
 #endif  // CHROME_COMMON_NATIVE_WEB_KEYBOARD_EVENT_H_