Only enable speech dispatcher on Linux with an explicit switch.

chrome/common/chrome_switches.h

 // 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.
 
 // Defines all the command-line switches used by Chrome.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 
 #include "build/build_config.h"
@@ skipping 387 matching lines @@
 
 #if defined(USE_ASH)
 extern const char kOpenAsh[];
 #endif
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_CHROMEOS)
 extern const char kPasswordStore[];
 #endif
 
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+extern const char kEnableSpeechDispatcher[];
 extern const char kMigrateDataDirForSxS[];
 #endif
 
 #if defined(OS_MACOSX)
 extern const char kDisableAppShims[];
 extern const char kDisableSystemFullscreenForTesting[];
 extern const char kEnableSimplifiedFullscreen[];
 extern const char kRelauncherProcess[];
 #endif
 
@@ skipping 23 matching lines @@
 #else
 extern const char kEnablePrintPreview[];
 #endif
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_