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

chrome/browser/browser_resources.grd

Index: chrome/browser/browser_resources.grd
diff --git a/chrome/browser/browser_resources.grd b/chrome/browser/browser_resources.grd
index b30eae211d84ca278ae62a96437922665b03f846..2f51d4520030471d2f705ffc829b0d0418fc3afa 100644
--- a/chrome/browser/browser_resources.grd
+++ b/chrome/browser/browser_resources.grd
@@ -301,9 +301,6 @@
         <!-- manifest file of Connectivity Diagnostics app -->
         <include name="IDR_CONNECTIVITY_DIAGNOSTICS_MANIFEST" file="resources\chromeos\connectivity_diagnostics\manifest.json" type="BINDATA" />
         <include name="IDR_CONNECTIVITY_DIAGNOSTICS_LAUNCHER_MANIFEST" file="resources\chromeos\connectivity_diagnostics_launcher\manifest.json" type="BINDATA" />
-        <!-- manifest file of built-in speech synthesis extension -->
-        <include name="IDR_SPEECH_SYNTHESIS_MANIFEST" file="resources\chromeos\speech_synthesis\manifest.json" type="BINDATA" />
-        <include name="IDR_SPEECH_SYNTHESIS_GUEST_MANIFEST" file="resources\chromeos\speech_synthesis\manifest_guest.json" type="BINDATA" />
         <include name="IDR_DRIVE_INTERNALS_CSS" file="resources\chromeos\drive_internals.css" type="BINDATA" />
         <include name="IDR_DRIVE_INTERNALS_HTML" file="resources\chromeos\drive_internals.html" flattenhtml="true" type="BINDATA" />
         <include name="IDR_DRIVE_INTERNALS_JS" file="resources\chromeos\drive_internals.js" type="BINDATA" />