Only enable speech dispatcher on Linux with an explicit switch.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 100d8443ab03106ad2dd4fffb619a3a3477d35e2..0dbf04b75834ad242a6f7b246d30e9ae678a6f12 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1444,6 +1444,11 @@ const char kPasswordStore[]                 = "password-store";
 // and sanity checks are made to avoid corrupting the profile.
 // The browser exits after migration is complete.
 const char kMigrateDataDirForSxS[]          = "migrate-data-dir-for-sxs";
+
+// Allows sending text-to-speech requests to speech-dispatcher, a common
+// Linux speech service. Because it's buggy, the user must explicitly
+// enable it so that visiting a random webpage can't cause instability.
+const char kEnableSpeechDispatcher[] = "enable-speech-dispatcher";
 #endif  // defined(OS_LINUX) && !defined(OS_CHROMEOS)
 
 #if defined(OS_MACOSX)