Disable speech synthesis API for content/ layer.

content/shell/browser/shell_content_browser_client.cc

Index: content/shell/browser/shell_content_browser_client.cc
diff --git a/content/shell/browser/shell_content_browser_client.cc b/content/shell/browser/shell_content_browser_client.cc
index 83fe76f20b3e1e5e7ce0425294d6de0c1d025790..6f5fefd9b686ab6ef22c9d05a59f848af6399389 100644
--- a/content/shell/browser/shell_content_browser_client.cc
+++ b/content/shell/browser/shell_content_browser_client.cc
@@ -237,6 +237,10 @@ void ShellContentBrowserClient::AppendExtraCommandLineSwitches(
         CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
             switches::kRegisterFontFiles));
   }
+
+  // Speech Synthesis backend lives in chrome/. See crbug.com/347045
+  // tracking moving it to content/.
+  command_line->AppendSwitch(switches::kDisableSpeechSynthesis);
 }
 
 void ShellContentBrowserClient::OverrideWebkitPrefs(