Remove unnecessary call to EnableFileSystemInGuestMode

This call makes no sense. There's no reason that loading the
speech synthesis component extension should trigger enabling
the filesystem in guest mode for a related, but entirely different,
extension (ChromeVox).

If ChromeVox needs EnableFileSystemInGuestMode, we should be calling
this from code that loads the ChromeVox component extension, but I suspect
that it doesn't need it at all.

As far as I can tell this was accidentally added here as part of a
refactoring:
  https://codereview.chromium.org/1162283002

Note that OnceClosure() would be better, but that'd require a big cleanup
of many other functions, so I don't want to do that as part of the same
change.

Bug: none
Change-Id: I1f67b78548048fffa9194083b10e0ff5c5aaa863
Reviewed-on: https://chromium-review.googlesource.com/1246364Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594463}

chrome/browser/extensions/component_loader.cc

@@ -368,10 +368,7 @@ void ComponentLoader::AddNetworkSpeechSynthesisExtension() {
 void ComponentLoader::AddChromeOsSpeechSynthesisExtension() {
   AddComponentFromDir(
       base::FilePath(extension_misc::kSpeechSynthesisExtensionPath),
-      extension_misc::kSpeechSynthesisExtensionId,
-      base::Bind(&ComponentLoader::EnableFileSystemInGuestMode,
-                 weak_factory_.GetWeakPtr(),
-                 extension_misc::kChromeVoxExtensionId));
+      extension_misc::kSpeechSynthesisExtensionId, base::RepeatingClosure());
 }
 #endif