Remove a bunch of TOOLKIT_GTK in content/ and gpu/, as well as NPAPI plugins on linux

content/shell/renderer/test_runner/key_code_mapping.h

 // 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.
 
 #ifndef CONTENT_SHELL_RENDERER_TEST_RUNNER_KEY_CODE_MAPPING_H_
 #define CONTENT_SHELL_RENDERER_TEST_RUNNER_KEY_CODE_MAPPING_H_
 
 namespace content {
 
 // The keycodes match the values of the virtual keycodes found here
@@ skipping 16 matching lines @@
     VKEY_F1       = 0x70,
     VKEY_NUMLOCK  = 0x90,
     VKEY_LSHIFT   = 0xA0,
     VKEY_RSHIFT   = 0xA1,
     VKEY_LCONTROL = 0xA2,
     VKEY_RCONTROL = 0xA3,
     VKEY_LMENU    = 0xA4,
     VKEY_RMENU    = 0xA5,
 };
 
-// Map a windows keycode to a native keycode on defined(__linux__) && defined(TOOLKIT_GTK).
-int NativeKeyCodeForWindowsKeyCode(int keysym);
-
 }  // namespace content
 
 #endif  // CONTENT_SHELL_RENDERER_TEST_RUNNER_KEY_CODE_MAPPING_H_