Load the Chrome OS TTS engine manifest from the file system isntead of resources.

chrome/browser/extensions/component_loader.h

Index: chrome/browser/extensions/component_loader.h
diff --git a/chrome/browser/extensions/component_loader.h b/chrome/browser/extensions/component_loader.h
index 3eff82c5d11b2d9349923d0d43ff25c77ffef060..51e5d827a5b0804909d7820594d7598c9292aa88 100644
--- a/chrome/browser/extensions/component_loader.h
+++ b/chrome/browser/extensions/component_loader.h
@@ -103,7 +103,7 @@ class ComponentLoader {
   // NOTE: |done_cb| is not called if the component loader is shut down
   // during loading.
   void AddChromeVoxExtension(const base::Closure& done_cb);
-  std::string AddChromeOsSpeechSynthesisExtension();
+  void AddChromeOsSpeechSynthesisExtension();
 #endif
 
   void set_ignore_whitelist_for_testing(bool value) {
@@ -164,11 +164,20 @@ class ComponentLoader {
   void EnableFileSystemInGuestMode(const std::string& id);
 
 #if defined(OS_CHROMEOS)
-  // Used as a reply callback when loading the ChromeVox extension.
-  // Called with a |chromevox_path| and parsed |manifest| and invokes
+  // Adds an extension where the manifest file is stored on the file system.
+  // |manifest_filename| can be relative to the |root_directory|.
+  void AddWithManifestFile(
+      const base::FilePath::CharType* manifest_filename,
+      const base::FilePath& root_directory,
+      const char* extension_id,
+      const base::Closure& done_cb);
+
+  // Used as a reply callback by |AddWithManifestFile|.
+  // Called with a |root_directory| and parsed |manifest| and invokes
   // |done_cb| after adding the extension.
-  void AddChromeVoxExtensionWithManifest(
-      const base::FilePath& chromevox_path,
+  void FinishAddWithManifestFile(
+      const base::FilePath& root_directory,
+      const char* extension_id,
       const base::Closure& done_cb,
       scoped_ptr<base::DictionaryValue> manifest);
 #endif